Already out of contention for the top four having won just two of their first 10 games, Mumbai confirmed before the match that batter Suryakumar Yadav would miss the rest of the season with a left forearm injury.
However, Bumrah gave their fans something to cheer with a remarkable display of pace bowling, taking figures of 5-10 as KKR were restricted to 165-9.
Yet that total proved well beyond Mumbai as Pat Cummins and Andre Russell thrived with ball in hand to help KKR to their fifth win of the campaign.
A positive start from KKR that saw Ajinkya Rahane (25) and Venkatesh Iyer (43) put on 60 for the opening wicket eventually gave way to a Bumrah masterclass.
The turning point in their innings came in the 15th over as Bumrah removed Russell (9) and Nitish Rana (43) to reduce KKR to 139-5.
KKR never recovered from there and were helpless in the 18th as Bumrah produced a triple-wicket maiden.
Mumbai failed to deliver a batting effort to match his performance with the ball, the tone set when Rohit Sharma (2) was given out caught behind on review from the sixth ball of the reply.
Ishan Kishan (51) was the only Mumbai batter to score more than 15, Cummins displacing him in the 15th over, which also saw Daniel Sams (1) and Murugan Ashwin (0) caught to turn the tide firmly in KKR's favour.
The final three dismissals all came via run-outs as Mumbai's increasingly desperate chase ended with them bowled out for 113.
Bumrah blitz
India fast bowler Bumrah's figures marked the best of his IPL career, beating the 4-14 he took against Delhi Capitals in 2020.
The highlight was unquestionably the 18th over, in which Sheldon Jackson and Cummins both fell before Bumrah had Sunil Narine caught and bowled. Tim Southee denied him a sixth wicket and a hat-trick.
KKR still in the hunt
Defeat for KKR would have ended their top-four hopes. As it is, they still have an outside chance of making the play-offs. They are one of four teams on 10 points, four points behind fourth-placed Royal Challengers Bangalore.
However, three of those teams have a game more to play, meaning KKR's fate is therefore not in their own hands.
The Indians put their opponents in to bat first but no doubt soon regretted that decision as opener Buttler plundered 100 off 68 balls.
That knock did the heavy lifting in the Royals' 193-8 – a total that proved comfortably beyond Mumbai, despite the best efforts of teenager Tilak Varma (61).
Buttler had 26 runs in a dizzying fourth over alone and later put on 82 with captain Sanju Samson (30) for the third wicket in the biggest partnership of the match.
Shimron Hetmyer (35) played his part and the Royals were moving at a blistering pace up until his departure, collapsing from 183-3 with 11 balls remaining.
That shaky finish looked like it could prove costly when Varma joined Ishan Kishan (54) in the middle, but Ravi Ashwin finally got the better of the 19-year-old.
Yuzvendra Chahal (2-26) then set about tidying up the rest of the middle order, getting Tim David and Daniel Sams from consecutive deliveries before creating a hat-trick chance with his ball to Murugan Ashwin, only for Karun Nair to fluff the catch, if not his team's ultimately routine win.
Bumrah bests Buttler after brilliant show
One of the great limited-overs batsmen, Buttler's tally of a single hundred in 66 prior IPL matches was on the light side. He was well on the way to his second century within four overs, though, with 38 runs off 20 balls at that stage.
The England wicketkeeper hit five boundaries in succession – two fours and three sixes – in that fourth over. Although that pace then slowed a little, it still required an elite bowler to eventually get Buttler, with a Jasprit Bumrah beauty among three wickets in the 19th over as he finished with 3-17.
Victory charge ends with Varma wicket
Varma could not join Buttler on three figures, but this was a first fifty and will surely not be his last. It said a lot for Varma's performance that he earned a send off from Ashwin, having sent him for six with a reverse sweep from the previous ball.
Unfortunately for the Indians, already slightly behind in the game, their next boundary did not follow for almost three overs – during which time Chahal took his two wickets.
This year's tournament was suspended indefinitely back on May 4 amid a rise in COVID-19 cases within the bio-secure bubbles set up for the teams in India.
The Board of Control for Cricket in India have since announced the final 31 games will be staged in Dubai, Sharjah and Abu Dhabi instead, starting with Chennai Super Kings against Mumbai Indians on September 19.
While the Royals sit just outside the top four ahead of the resumption overseas, they have been dealt a blow following confirmation Buttler will miss the rest of the campaign.
The England wicketkeeper-batsman is expecting a second child with his partner and will not be part of the Rajasthan squad, as confirmed by the team on social media on Saturday.
New Zealander Glenn Phillips has been signed as a replacement for Buttler, who scored 254 runs an at an average of 36.28 in his seven appearances earlier this year, including making 124 – his maiden T20 hundred – against Sunrisers Hyderabad.
Buttler is currently part of England's Test squad taking on India in a five-match series on home soil, which will be followed by a busy winter schedule.
The rearranged T20 World Cup takes place in October and November, while the following month sees the start of the Ashes series in Australia.
The England white-ball skipper rattled off another superb knock of 52 to continue his rich vein of form during Wednesday's clash at M. A. Chidambaram Stadium.
But his side's tally of 175-8 was almost knocked off by a pyrotechnic finale from MS Dhoni and Ravindra Jadeja, who crashed 36 runs off the final two overs.
Despite the early loss of fellow opener Yashasvi Jaiswal (10), it was Buttler's sturdy second-wicket partnership with Devdutt Padikkal (38) that kept Rajasthan ticking over.
Even when their 77-run stand came to an end, subsequent turns from Ravichandran Ashwin (30) and Shimron Hetmyer (30 not out) continued to punish a loose bowling attack.
Jadeja's tidy 2-21 off four overs came too late to restrict the damage, and CSK were forced straight onto the offensive themselves when they came to the crease in pursuit.
For a while, it looked like they would prove handily successful in their chase, before the loss of Devon Conway (50) and Ajinkya Rahane (31) saw them tumble to 113-6.
But then, with their side in need, the veteran duo of Dhoni (32 not out) and Jadeja (25 not out) almost dragged them over the line, finishing just shy with 172-6 after Sandeep Sharma held his nerve in the final over.
Buttler continues IPL brilliance
Having led England to T20 World Cup glory last year, there was little doubt the wicketkeeper-batter's form would again be a big-time player for the Royals, and so it has been proven.
After 54 against the Sunrisers and 79 against the Capitals, he has once again shown himself invaluable to the Royals and their hopes of success this season.
Dhoni rolls back the years
Having needed 40 runs off the final dozen balls, it appeared a stretch too far even for the 41-year-old and his superb skills.
But he hasn't hung up his pads yet for a reason, and his devastating knock, with three maximums and an additional four, helped set up the grandstand finish.
Buttler made a mockery of Kolkata's decision to put Rajasthan into bat, hammering a 59-ball century to power the Royals to 217-5.
It was his second hundred of the season, making him only the sixth player to score multiple centuries in a single IPL campaign.
The Knight Riders put together an excellent chase, Aaron Finch (58) and captain Shreyas Iyer (85) putting on 107 for the second wicket.
Yuzvendra Chahal (5-40) looked to have ended their hopes in the 17th over by taking four wickets, the crucial scalp of Shreyas marking the start of a hat-trick, to reduce the Knight Riders to 180-8.
An unlikely batting cameo from Umesh Yadav, who struck 21 off nine, had Kolkata in position to snatch victory, but debutant Obed McCoy removed Sheldon Jackson before bowling Yadav to clinch it for Rajasthan with two balls to spare.
Buttler at his blistering best
Having already struck 100 against Mumbai Indians, an effort followed by a further two half centuries in his last three games, Buttler has started the season in ominous form.
Kolkata were the latest side to fall victim to his destructive batting, Buttler hitting nine fours and five sixes on his way to 103.
He joins Chris Gayle (2011), Virat Kohli (2016), Hashim Amla (2017), Shane Watson (2018) and Shikhar Dhawan (2020) in scoring multiple hundreds in a season.
Chahal sparks collapse, Obed the real McCoy
There was jubilation for Rajasthan as Chahal claimed their fifth IPL hat-trick when he had Pat Cummins caught behind.
Yadav extinguished any thoughts of a procession from there, but McCoy – playing his first cricket since a right leg injury ended his involvement in West Indies' T20 World Cup campaign last October – rose to the occasion in his maiden IPL match to finish the job. The Royals are now second on eight points, two ahead of KKR.
An opening partnership of 98 from Buttler and Yashasvi Jaiswal from just 8.3 overs gave the Royals a foundation to build from, eventually setting the Capitals a target of 200.
Three wickets each for Trent Boult and Yuzvendra Chahal then reduced Delhi as they could only muster 142-9 from their 20 overs.
Buttler and Jaiswal set the tone before the latter was caught and bowled by Mukesh Kumar for 60 from just 31 deliveries.
Delhi gave themselves hope of causing a batting collapse as Kuldeep Yadav removed captain Sanju Samson for a duck, before Rovman Powell bowled Riyan Parag for seven to reduce the Royals to 126-3 as the run rate began to slow down.
Buttler continued to keep the scoreboard ticking along with Shimron Hetmyer (39 not out), though, before also being caught and bowled by Mukesh.
Boult dismissed Prithvi Shaw and Manish Pandey for ducks as the Capitals slipped to 0-2 inside the first over of their reply.
After Rilee Rossouw was out for 14, David Warner and Lalit Yadav started to finally allow Delhi to get a foothold in their innings before the latter was bowled by Boult for 38.
Warner started to quickly run out of partners before finally succumbing himself for 65 as the Capitals struggled to ever threaten the target to give the Royals their second win to go top of the Indian Premier League, while Delhi suffered their third loss from three outings.
Buttler storms the Capitals
It was a mature knock from the England white-ball captain, who hit 11 fours and one six, though he did have a lucky moment when he was dropped on 18 by Anrich Nortje.
He briefly sat atop the IPL's list for most runs in the early stage of this year's competition (152), only for Warner (158) to overtake him in Delhi's reply.
Warner landmark no consolation for Delhi
The Australian is the third batsman to score 6,000 runs in IPL history and the fifth to score 2,000 runs for the Capitals in the competition, and is only the second to score 2,000+ runs for two teams (also Sunrisers Hyderabad) after Shikhar Dhawan for the same two teams.
However, the Capitals have won just one IPL game from the last 14 times they have chased a target of 200 or more, which was a seven-wicket win when chasing Gujarat Lions' score of 208 in May 2017.
The Sunrisers, bottom of the standings with six defeats from seven, made the dramatic decision to strip David Warner of their captaincy on Saturday and there was no place in their XI for the deposed Australia opener.
Buttler proceeded to provide the sort of fireworks at the top of the order that are seemingly beyond Warner at present, plundering a maiden T20 ton in style as he smashed 124 from 64 deliveries, with 11 fours and eight sixes, to account for the bulk of an imposing 220-3.
Despite the promise of first-wicket stand of 57 between Manish Pandey (31) and Jonny Bairstow (30), Hyderabad's chase never really threatened and they limped to 165-8 – left-arm seamer Mustafizur Rahman (3-20) the pick of the Rajasthan attack.
Although he had twice come close with knocks of 49 and 41, Buttler entered the match without a half-century to his name in six previous attempts this season.
The England star was not initially at his fluent best, gutsing his way to a 39-ball fifty after surviving an lbw shout from Rashid Khan on seven, the leg-spinner dismissing Buttler's opening partner Yashasvi Jaiswal for 12 in similar fashion.
Supported by skipper Sanju Samson (48) in a 150-run stand for the second wicket, Buttler cut loose. The 15th over, Mohammad Nabi's sole contribution with the ball, disappeared for 21, and by the time Sandeep Sharma (1-50) forced him to drag on, Buttler had already walloped three sixes and a four from the penultimate over.
Pandey and Bairstow made light of Warner's axing, although Mustafizur bowled the former off his pads with a slower ball and the procession that followed Buttler's England colleague perishing at long-on off Rahul Tewatia (1-45) showed Hyderabad's problems are myriad.
New skipper Kane Williamson scored 20 off 21 deliveries and any lingering hope was gone when he became Kartik Tyagi's first IPL wicket.
Kedar Jadhav's run-a-ball 19 was the best any one else could muster and he was bowled to be one of three victims for Chris Morris (3-29).
Patience pays off for Buttler
It seems unusual to flag up how a batsman who flayed the opposition to all parts actually played within himself initially, but Buttler shrewdly recognised his way out of a relative slump. "I think sometimes you have to swallow your ego when you're not in perfect touch," he said when receiving the man-of-the-match award.
"You have to give yourself time and find your way. I tried to stay in and keep the belief that something will click." As the final 25 deliveries Buttler faced disappeared for 74, it was fair to say something exploded.
A new role for Rashid
Khan was into the attack early for Hyderabad, Williamson breaking from Warner's habit of using the spinner in the middle overs. The skipper was partially vindicated by the early wicket and it would have been a very different contest had Buttler not survived.
However, Khan's allocation being used by the 11th over arguably left the Sunrisers exposed to one of the most destructive batsman on the planet and lacking the means to check his charge.
Buttler has been in immaculate form in the Indian Premier League, scoring successive centuries in the previous two matches, but he lasted just nine balls in Pune on Tuesday.
The England international's score of eight included one boundary before he was dismissed by Josh Hazlewood (2-19) in the fifth over.
Sanju Samson struck an entertaining 27, including three sixes, to get the Royals back on track, though it was Parag who ultimately dragged them through.
Having anchored the back half of the Royals' innings, Parag let rip in the final over, plundering two sixes and a four to get his side to 144-8.
Faf du Plessis elected to go with Virat Kohli at the top of the order, but RCB's former captain went for nine in the second over.
Du Plessis tallied up 23 before he fell to Sen, who had Glenn Maxwell for a golden duck with the next delivery.
Ravichandran Ashwin (3-17) joined the party, dismissing Rajat Patidar, Suyash Prabhudessai and Shahbaz Ahmed, while Dinesh Karthik was run out.
Wanindu Hasaranga (18) offered some resistance for RCB, though their hopes of avoiding a second straight defeat ended when Sen wrapped up the tail as Rajasthan went top of the IPL on 12 points.
Parag takes up the mantle
With Buttler failing to ignite, Parag initially showed great composure before that explosive final over when he reached a 29-ball half-century. Harshal Patel, who took 1-33, was the unlucky bowler, with 18 runs coming from those last six balls.
More frustration for Kohli
It was another bad day at the office for Kohli, who has failed to reach double figures in five of his nine IPL innings in 2022. Indeed, it was a bad day all round for the Challengers, who could have gone top with a win, with only Du Plessis scoring above 20.
The Royals had lost six of their last seven matches heading into a meeting with a CSK side that also started the day on six points from nine games.
CSK won the toss and their decision to bat first ultimately proved ill-advised, though Rajasthan initially laboured in pursuit of 126.
Buttler came to the crease with the Royals teetering on 28-3 in the fifth over and had to exercise patience alongside Steve Smith (26 not out) before being able to cut loose.
When he was able to get into his rhythm, Buttler produced his brilliant best, hitting seven fours and a pair of sixes in a 48-ball knock that helped Rajasthan move within two points of the top four
CSK earlier recovered from 56-4 to reach 125-5 thanks to a fifth-wicket stand between MS Dhoni (28) and Ravindra Jadeja (35 not out), however, a run out of the former by Jofra Archer and Sanju Samson proved key in keeping them under 130.
ARCHER EXCELS AGAIN
Archer has been outstanding for Rajasthan, adding to his reputation as one of the world's most fearsome fast bowlers in all formats.
He was excellent again on Monday, removing Faf du Plessis with the final ball of the third over and sending down 11 dot balls in his 1-20.
The England paceman ran out CSK skipper Dhoni to end an ominous partnership with Jadeja, though the Royals initially made heavy weather of a manageable chase.
BUTTLER LEADS ROYALS RESURGENCE
Though he and Smith had to deal with some concerted pressure early in their decisive stand of 98, Buttler eventually got his reward for frustrating the CSK attack.
His was an innings typically defined by precision and timing and a 15th over that saw Buttler hit England colleague Sam Curran for three successive fours effectively took the game away from CSK.
Rajasthan were left needing just 18 off the final five overs and there was to be no dramatic collapse, Jadeja falling over the boundary rope at long-on for Buttler's final six in the 17th over before Smith then hit the winning run.
The Capitals posted 159-4 on a slow pitch at MA Chidambaram Stadium, Prithvi Shaw top-scoring with 53 from 39 balls and Rishabh Pant (37) and Steve Smith (34) both adding handy contributions.
Sunrisers looked beaten when Axar took two wickets in as many balls to reduce them to 117-6 in the 17th over, but Kane Williamson's unbeaten 66 from 51 deliveries kept them in the hunt.
They needed 16 to win off the last over from Kagiso Rabada and forced the Super Over after a boundary from Williamson and Jagadeesha Suchith's huge six over midwicket.
Williamson and David Warner were then restricted to just seven runs by Axar, who was handed the ball for the Super Over in his first match of the tournament after recovering from coronavirus.
Sunrisers were deducted a run as Warner's bat did not cross the line as he scampered back for a second off the final ball of Axar's over.
Shikhar Dhawan struck a boundary before he and Pant went through for a third leg bye of Rashid Khan's decisive over to secure a fourth victory from five matches for second-placed Delhi, who are level on points with leaders Chennai Super Kings.
Williamson did not deserve to be on the losing side after making an excellent half-century following Jonny Bairstow's blistering 38 from 18 balls, which included four sixes. Avesh Khan claimed 3-34 for the Daredevils.
Shaw steps up at the top of the order
The first three balls of the match sent down by Khaleel Ahmed were dispatched for four by Shaw and the Capitals had 26 on the board after two overs.
Shaw reached his half-century off 35 balls, with Dhawan bowled by Rashid Khan for 28 to end an opening stand of 81 in the 11th over.
Pant and Smith struck a six apiece after Shaw was run out, putting on 58 for the third wicket on a slow track with runs not easy to come by.
Axar makes up for lost time
Spinner Axar was stuck in quarantine as the Capitals made a promising start to the season following a positive COVID-19 test that brought him back down to earth after an outstanding Test series against England.
Avesh Khan removed Bairstow immediately after the England wicketkeeper-batsman hit him for six, after Warner had been run out for six, and the same bowler also saw the back of Virat Singh.
Axar was on a hat-trick after trapping Abhishek Sharma and Rashid Khan in the 17th over, and he bowled a tight Super Over to ensure Williamson's brilliant knock was in vain.
Having lost their first five matches, Delhi got off the mark with a win over Kolkata Knight Riders last week, and they followed it up with a seven-run success over Sunrisers.
The Capitals, despite strong contributions from Manish Pandey (34) and Axar Patel (34) failed to set an imposing total. Washington Sundar (3-28) helping Sunrisers restrict them to 144-9.
Sunrisers looked poised to canter to 145 when Mayank Agarwal (49) guided them to 69-1. However, they subsequently lost four wickets for 16 runs, leaving Heinrich Klaasen (31) and Sundar (24 not out) to lead a recovery mission.
Though Klaasen fell with nine balls remaining, Sundar was in a position to get them over the line, Sunrisers needing 13 off the last.
But Mukesh Kumar did not allow a single boundary in the final six balls, frustrating Sunrisers with superb death blowing to seal triumph for Delhi.
Delhi celebrate new low
The Capitals' total of 144 is the lowest they have successfully defended in the IPL. Their previous best in that regard came back in 2009, when they prevailed against Rajasthan Royals when defending 150.
Bhuvneshwar brilliance not enough
Bhuvneshwar Kumar will feel aggrieved to be on the losing side. The Sunrisers seamer bowled 16 dot balls in his four overs, the most by any bowler this season. His 11 runs conceded also marked the lowest total by any bowler to complete his allocation of overs in the 2023 campaign.
The Kings were put into bat by the Capitals and that decision paid off in a substantial way as their attack thrived in Mumbai.
Axar Patel (2-10) and Lalit Yadav (2-11) were the pick of the bunch as the Kings were bowled out for 115.
Captain Mayank Agarwal (24) and Jitesh Sharma (32) were the only batters to score more than 20 for the Kings.
Prithvi Shaw (41) and David Warner (60 not out) put on the highest powerplay score of the season as the Capitals raced to 81-0.
There was never any way back for the Kings from there, Warner finishing things off with a boundary to seal Delhi's third win of the season.
Kings fade after steady start
The Kings put on an opening stand of 33 but then lost four wickets in the space of three overs for 21 runs as the Delhi attack seized control.
Jitesh provided hope during his 23-ball stay at the crease, but the tail was unable to repair the damage after he was removed by Axar.
Warner finishes with a flourish
Warner's half-century was his 53rd in IPL cricket and made it three in a row for the Australia opener. He wrapped up the win with 57 balls to spare with a fine pull shot to the midwicket boundary.
The Capitals, requiring a victory at the Wankhede Stadium to make the last four, were limited to 159-7, with Jasprit Bumrah (3-25) the pick of the bowlers.
Rovman Powell (43) and Rishabh Pant (39) fell short of half-centuries, but Delhi's total looked competitive as the Indians made a slow start in response.
Mumbai struggled to 27-1 at the end of the powerplay after Anrich Nortje dismissed captain Rohit Sharma, who managed only two off 13 deliveries.
Ishan Kishan offered more attacking intent, scoring 48 off 35 balls before falling to Kuldeep Yadav (1-33) in the 12th over and Dewald Brevis (37) followed to Shardul Thakur soon after with 65 runs still required.
Pant failed to review when David, on nought, edged behind and the Australian capitalised by blasting an 11-ball 34 before he was removed by Thakur (2-32) to leave Mumbai needing just 15 from 13 balls.
Ramandeep Singh (13 not out) saw Rohit's side over the line with five deliveries to spare, which meant Royal Challengers Bangalore took the final play-off spot and will face Lucknow Super Giants in the eliminator on Wednesday.
Brilliant Bumrah
Bumrah has been somewhat off the pace for the struggling Mumbai in this year's competition, barring his excellent 5-10 against Kolkata Knight Riders.
However, the India quick was in imperious form in the first innings of this game, removing Prithvi Shaw (24), Mitchell Marsh (nought) and Powell to take his tally to 15 in the 2022 IPL.
Pant's reviews
Pan dropped a simple chance when Brevis skied Kuldeep on 25. The skipper then ignored Thakur's advice and opted to not review when David edged behind.
The Capitals captain followed that up by reviewing a Nortje delivery to Tilak Varma that pitched well outside leg stump, capping a miserable day for the India wicketkeeper.
Marcus Stoinis made 53 from 21 deliveries as Delhi recovered from a shocking start to post 157-8, though their fightback appeared in vain when their opponents matched their total with three balls to spare.
However, needing just one more run to prevail, Kings XI were somehow unable to get over the line, losing wickets off the final two deliveries.
Mayank Agarwal was the first of those to depart having made a superb 89, the opener rescuing his side after they had slipped to 55-5 in their reply.
He hit 10 runs off Stoinis' first three deliveries at the start of the 20th over, but the bowler hit back when a wide full toss was slapped to Shimron Hetmyer in the deep.
Chris Jordan then clipped a full toss straight to Kagiso Rabada at square leg to leave the scores level, meaning a super over was required to decide the outcome of a see-saw contest.
Kings XI managed two runs off the opening ball but Rabada then claimed a pair of wickets, leaving Delhi needing three. They easily reached the paltry target to snatch victory from the jaws of defeat.
STOINIS STUNS KINGS XI
Having come together at 13-3, Shreyas Iyer and Rishabh Pant made 39 and 31 respectively. Still, when both fell in successive balls, the Capitals were reeling at 87-5.
Stoinis, though, emphatically changed the tempo of the innings. Kings XI leaked 57 from the final three overs – including 30 off the last, bowled by Chris Jordan – as Delhi finished with a flourish.
PAINFUL OUTING FOR ASHWIN
Playing against his former franchise, Ravichandran Ashwin's involvement was cut short when he suffered an apparent shoulder injury.
The India spinner claimed two wickets in his opening over before getting hurt when diving to stop a ball, forcing him to leave the field with his left arm in a makeshift sling.
PAIR FOR POORAN
It is not often you get to bat twice in a Twenty20 game. However, Nicholas Pooran failed to capitalise on either opportunity he had for Kings XI.
The West Indies batsman was dismissed by Ashwin first time around and then, called into action again in the super over, was cleaned up first ball by Rabada.
Both sides were already assured of a play-off spot before they met at the Dubai International Stadium and it was the Capitals who moved to the brink of sealing a top-two finish with their 100th victory in the IPL's 50th match of 2021.
Kagiso Rabada steered Dwayne Bravo for four to take Delhi beyond their target of 137 to win, moving above their opponents with one game of the regular season to play.
Ambati Rayudu top scored with an unbeaten 55 from 43 balls in CSK's total of 136-5 after they were put in by birthday boy Rishabh Pant, Axar Patel the pick of the bowlers with 2-18 from his four overs.
Shikhar Dhawan struck 39 off 35 deliveries in his 300th T20 game, but Delhi collapsed to 99-6 after the opener and Ravichandran Ashwin fell in an excellent 15th over from Shardul Thakur (2-13)
Ravindra Jadeja (2-28) had earlier removed Pant and Ripal Patel, into the side at the expense of Steve Smith, but a dropped catch from Krishnappa Gowtham and some wayward Dwayne Bravo bowling cost CSK.
Substitute fielder Gowtham dropped a simple chance offered by Shimron Hetmyer in the 18th over and the West Indies batsman finished unbeaten on 28, with Rabada settling a tight contest.
Axar peaking at the right time
Spinner Axar was named man of the match after taking 3-21 in a four-wicket win over defending champions Mumbai Indians on Saturday.
The tweaker made a big impact once again two days later, getting dangerous duo Faf du Plessis and Moeen Ali caught at deep midwicket.
Axar has taken 14 wickets in IPL games, with his economy rate of 6.05 the sixth-best in the tournament, and he could have a big say in whether Delhi win the title.
Gowtham gaffe punished
The Capitals needed 28 to win off three overs after losing their way in the run chase, but the game swung back in their favour in the 18th over.
Bravo had already bowled two wides and been hit for four by Hetmyer before his Windies team-mate was put down by Gowtham coming in from long-on, the ball going through his hands and crossing the ropes to add insult to injury.
Hetmyer launched Josh Hazlewood for a huge six into the leg side in the next over as Gowtham looked to the skies in disbelief.
A strong batting performance that benefited from a late onslaught by the big-hitting Marcus Stoinis powered Delhi to 196-4 after they had been put into bat by Virat Kohli.
Prithvi Shaw (42) was the aggressor in an opening stand worth 68 with Shikhar Dhawan, who contributed a more sedate 32 to the cause before departing in the 10th over.
Rishabh Pant made 37 but it was Stoinis who stole the show in the closing overs, the Australian all-rounder blasting six fours and a pair of sixes as he made an unbeaten 53.
Bangalore's reply simply never recovered after a poor start that saw them slip to 43-3, AB de Villiers among those to fall early.
Captain Kohli top-scored with 43 before becoming one of four wickets for the excellent Kagiso Rabada, who now has 12 in this year's tournament at an average of 12.50.
There were two wickets apiece for Anrich Nortje and Axar Patel too, the Royal Challengers eventually finishing well shy on 137-9 from their 20 overs.
STOINIS STUNS ROYAL CHALLENGERS
Stoinis had endured a lean spell since starting the new IPL season with 53 against Kings XI Punjab in Delhi's opener.
He had managed just 16 runs in three knocks since but was back to his destructive best against Bangalore, reaching his half-century off 24 deliveries as he added 89 for the third wicket with Pant.
FINCH SPARED DESPITE R-ASH MOVE
In 2019, Ravichandran Ashwin caused a stir when, as captain of Kings XI, he ran out Rajathan Royals' Jos Buttler at the non-striker's end, the batsman having left his crease before the ball had been delivered.
There was nearly a repeat when Ashwin had a similar situation with Aaron Finch here, but the India spinner opted instead to produce a stare at the out-of-position Bangalore batsman, followed quickly by a wry smile.
The Capitals were at the summit when the tournament was halted in May due to the coronavirus pandemic and returned to the top by making a statement at the Dubai International Cricket Stadium on Wednesday.
Third-placed Sunrisers were rocked by a positive COVID-19 test for bowler T Natarajan ahead of the match, resulting in Vijay Shankar being among a further six members of the franchise to be forced into isolation.
Their day did not get any better in the first game for the two sides since the IPL resumed, with Sunrisers only posting 134-9 as Anrich Nortje (2-12), Axar Patel (2-21) and Kagiso Rabada (3-37) did most of the damage.
Delhi coasted to victory, Shikhar Dhawan - the leading run-scorer in IPL 2021 - making 42 off 37 balls at the top of the order to lay the foundations.
The fit-again Shreyas Iyer top scored with 47 from 41 deliveries in his 150th IPL game and captain Rishabh Pant struck an unbeaten 35 off 21 balls as the Capitals moved two points clear of a Chennai Super Kings side who have a game in hand.
PROTEAS PACEMEN FIRE
Nortje was recruited by the Capitals after England all-rounder Chris Woakes opted against taking part in the remainder of the tournament.
The South Africa paceman made an instant impact, getting rid of David Warner for a duck with the third ball of the match before trapping Kedar Jadhav lbw.
Nortje bowled 14 dot balls and although his South Africa team-mate Rabada was much more expensive, he removed Wriddhiman Saha, Manish Pandey and Abdul Samad. Axar was also outstanding in an impressive display with the ball from Delhi.
DHAWAN DELIVERS AGAIN, IYER UP AND RUNNING
Dhawan is on a mission not only to claim the title but also win the purple cap and he leads KL Rahul (380) with 422 runs from nine matches after a blistering knock, striking a six and finding the rope six times.
Delhi suffered a blow when all-rounder Marcus Stoinis sustained a hamstring problem in the field, but Iyer gave the Capitals a big boost in his first game of the tournament and a landmark match.
A shoulder injury meant the batsman was unable to play any part before the tournament was halted on home soil and he teamed up with Pant, who succeeded him as captain, in a stand of 67 off 46 deliveries to seal an emphatic win.
The winner of the penultimate match of the regular season at Zayed Cricket Stadium was guaranteed to face Mumbai Indians in Qualifier 1 on Thursday and it was Delhi who came out on top.
RCB remain in the hunt for the title, though, progressing as their net run-rate is better than fourth-placed Kolkata Knight Riders finished with.
Sunrisers Hyderabad can seal the final play-off place at the expense of KKR if they beat defending champions Mumbai on Tuesday.
RCB posted 152-7 after being put in, the consistent Devdutt Padikkal making 50 off 41 balls and AB de Villiers 35 from 21 in Abu Dhabi on Monday.
South Africa pacemen Anrich Nortje (3-33) and Kagiso Rabada (2-30) played big hands for the Capitals once again to restrict Virat Kohli's side to a below-par total.
Dhawan (54 off 41) and Rahane (60 from 46) put on 88 for the second wicket to put the Capitals well on their way to victory.
PROLIFIC PADIKKAL, PROTEAS DUO STAR AGAIN
Padikkal has been one of the shining lights for RCB and the 20-year-old moved above his captain Kohli in the list of leading run-scorers in the 2020 tournament.
The opener matched KL Rahul's tally of five half-centuries in this year's competition, hitting five boundaries as he anchored the innings before the excellent Nortje removed his middle stump.
Ravichandran Ashwin, who opened the bowling, had Kohli caught in the deep for 29 off 24 balls and Rahane ran De Villiers out with a great throw in the final over after the wicketkeeper-batsman had cleared the rope twice.
Rabada, the leading wicket-taker in the tournament, has two more scalps than Jasprit Bumrah with 25 after dismissing Josh Philippe and Shivam Dube.
DHAWAN AND RAHANE DELIVER
Dhawan has also had an outstanding tournament and only his India team-mate Rahul has scored more runs than him.
The left-hander demonstrated majestic timing and power once again, finding the boundary six times as he and Rahane stepped up when their side needed them.
Rahane's half-century was his first in six knocks, a timely return to form, and he hit one of only two sixes in the run chase under pressure.
Shahbaz Ahmed saw the back of Dhawan and Shreyas Iyer before Rahane fell to Washington Sundar, but Rishabh Pant and Marcus Stoinis finished it off.
Avesh Khan (3-15) and Axar Patel (3-21) limited Mumbai - who are sixth with two matches to play - to 129-8 as the holders lost wickets at regular intervals.
Anrich Nortje also picked up 1-19 from his four-over allocation and, despite Suryakumar Yadav's 33, Rishabh Pant's side looked like the firm favourites at the halfway point in Sharjah on Saturday.
Nathan Coulter-Nile dismissed fellow Australian Steve Smith (nine) with his first delivery to leave the Capitals teetering at 30-3 after openers Shikhar Dhawan and Prithvi Shaw were also dismissed cheaply.
Pant (26) followed to off-spinner Jayant Yadav to leave Delhi 57-4 but Iyer and Shimron Hetmyer (15) offered resistance to drag their side up to 93-6 before the latter fell to Jasprit Bumrah's deceiving slower ball.
Ravichandran Ashwin (20) then joined Iyer, who finished unbeaten on 33, to secure victory for second-placed Delhi with five balls to spare and leave the Indians under serious threat of failing to reach the play-offs.
Avesh torments Indians
Avesh toyed with the Mumbai line-up as he delivered a mix of slower balls and inswinging yorkers to secure his three dismissals.
The seamer impressively dismissed the dangerous finisher Hardik Pandya in the penultimate over, while also removing Coulter-Nile after he had claimed the big scalp of Rohit Sharma in his first over.
Ashwin final-over gamble fails
Pant gambled by holding back Ashwin to the final over of Mumbai's innings. The off-spinner dismissed Jayant Yadav but conceded 13 from his final six deliveries as he ended with 1-41 from his four overs.
However, Ashwin made up for it with the bat as he sealed the win with a six off Krunal Pandya's first ball of the last over.
New Zealand wicketkeeper-batsman Tim Seifert became the latest Capitals player to return a positive test on the day of the match at Brabourne – CC.
Delhi had on Monday revealed that Australia all-rounder Mitchell Marsh had contracted COVID-19.
Tournament organisers gave the green light for the game against the Kings to be staged after the second round of tests all came back as negative.
The Board of Control for Cricket in India (BCCI) also announced that the Capitals' showdown with Rajasthan Royals on Friday has been moved from MCA Stadium in Pune to Wankhede Stadium in Mumbai.
That decision was made as a precautionary measure following Seifert's positive test.
