Singh shone with his maiden IPL five-wicket haul to bowl Rajasthan out for 185 with the final ball before Agarwal smashed 67 from 43 balls but that proved in vain due to Kartik Tyagi's magical final over to push the Royals to victory.
Evin Lewis (36) and Yashasvi Jaiswal (49) shared a 54-run opening stand as the Royals started rapidly, with Liam Livingstone (25) and Mahipal Lomror's 17-ball 43 providing further impetus.
However, Singh (5-32) and Mohammed Shami (3-21) pegged their opponents back with some superb death bowling to carry momentum forward to their innings.
KL Rahul (49), who was dropped three times, and Agarwal then put on 120 in 11.4 overs to propel Punjab Kings towards the target before Chetan Sakariya and Rahul Tewatia removed the respective openers.
Nicholas Pooran (32) and Aiden Markram (26 not out) steadied the ship to edge their side towards victory but, with just six required off the last over, Tyagi struck twice and conceded only four runs to steal victory from the jaws of defeat.
Poor fielding does not cost Rajasthan
Rahul could have been dismissed three times, with drops coming on two, 29 and 31 by Lewis, Riyan Parag and Sakariya, and then it would have been a completely different game.
Rajasthan failed to take their chances, gifting the openers the opportunity to build a match-winning stand,
Horrific Hooda
Deepak Hooda conceded 37 runs in two overs as Rahul's middle-overs gamble failed to pay off with the off-spinner carted around the ground before his two-ball duck at the end of Punjab's innings.
Indeed, Hooda only managed two dot balls in his 12-ball spell, with Lomror running riot in the 15th over as he launched 24 runs to push the Royals to a competitive total, which proved to just be enough.
After a 3-1 Test series defeat and a 3-2 setback in their T20I clashes with India, world champions England will look to end their tour on a high in three ODIs to be played in Pune over the next week.
Archer will be flying back home for checks on his injury, however, and the England and Wales Cricket Board (ECB) said he must also miss the start of the Indian Premier League (IPL).
That deals a blow to Rajasthan Royals ahead of the tournament that begins on April 9, with Archer having impressed against India in the T20 games.
The ECB said on Sunday: "Jofra Archer is returning to the UK for further management and investigation of his right elbow injury.
"Archer's elbow issue has deteriorated over the course of the Twenty20 International series and made it increasingly challenging for him to maintain performance levels. He has been deemed unfit for selection for the ODI series that features matches on 23, 26 and 28 March.
"The ECB medical team will assess the player and, together with Jofra, develop a treatment plan and a return-to-play schedule in due course. As a consequence, Jofra will miss the start of this year’s Indian Premier League."
England's ODI squad, aside from the obvious loss of Archer, is comprised of players selected for the T20 series and the reserves for those games.
England squad: Eoin Morgan (captain), Moeen Ali, Jonny Bairstow, Sam Billings, Jos Buttler, Sam Curran, Tom Curran, Liam Livingstone, Matt Parkinson, Adil Rashid, Jason Roy, Ben Stokes, Reece Topley, Mark Wood.
Also travelling with the squad: Jake Ball, Chris Jordan, Dawid Malan.
The pace bowler underwent surgery on his right hand towards the end of March having suffered damage to a finger while cleaning a fish tank.
Archer had also been bothered by a persistent elbow issue during the tour of India earlier in 2021, forcing him to miss the three-match one-day series against Virat Kohli's side.
The 26-year-old is set to resume full training with English county Sussex with the intention of making a playing comeback within the next two weeks.
"Archer returned to bowling this week with higher intensity, and the ECB and Sussex medical teams will continue to monitor his progress,” a statement from the ECB read.
"Archer will now step up his training regime starting next week and will be in full training with Sussex. It is expected that he will return to cricket in the next fortnight if he can continue to bowl and prepare pain-free.
"The ECB will confirm which matches he is expected to play in due course."
The absence of Archer is a huge blow for Rajasthan Royals, particularly as the IPL franchise have already lost England all-rounder Ben Stokes for the entire tournament due to a broken finger.
Archer claimed 20 wickets at an average of 18.25 in the Twenty20 competition for the Royals last year, posting an impressive economy rate of 6.55 runs per over.
Rajasthan have won just once in their opening four outings in the current campaign as they bid to qualify for the play-offs for the first time since 2018.
Archer was ruled out of the recent ODI series defeat to India with an elbow injury and underwent an operation on his hand on Monday, repairing damage done when he was cleaning a fish tank in January.
The quick will miss the start of the Rajasthan Royals' Indian Premier League campaign as he recovers from the procedure.
"England pace bowler Jofra Archer underwent successful surgery to his right hand on Monday. A fragment of glass was removed during the operation to his middle finger on his right hand." an ECB statement said.
"He will now commence two weeks of rehabilitation. The consultant will review him before returning to training.
"Further update on his elbow injury will be provided once he has returned to bowling to assess the effectiveness of his recent injection.
"Archer suffered a cut to his hand while cleaning at his home in January shortly before flying to India to prepare for the Test series.
"The ECB's medical team managed the injury throughout the tour, and it did not impact on his availability."
The Royals start their IPL campaign against Punjab Kings on Monday April 12.
Moeen Ali breezed to a 19-ball half-century as the Super Kings raced to 75-1 at the end of the powerplay, but they did not capitalise on their early impetus in Mumbai on Friday.
Spinners Yuzvendra Chahal (2-26) and Obed McCoy (2-20) were the pick of the bowlers to peg back Chennai, with MS Dhoni (26) the only other batter to pass 20 in support of Ali (93) in the Super Kings' 150-6.
Jos Buttler fell for just two to Simarjeet Singh (1-18) in response, before Sanju Samson (15) followed to Mitchell Santner (1-15) and Ali bowled Devdutt Padikkal (3) to leave the Royals 76-3 in the 12th over.
Opener Yashasvi Jaiswal batted on as his partners fell, making 59 off 44 balls before being dismissed by Prashant Solanki, with Rajasthan requiring a further 47 to win from the last five overs.
Solanki soon added the dangerous Shimron Hetmyer (6) to his list of scalps, but Ashwin – promoted up the order – took charge of the chase to see his side over the line with two balls to spare.
Victory meant Rajasthan will have two chances in the playoffs to make the final on May 29. Lucknow Super Giants must settle for third place.
Ali efforts in vain
All eyes were on Buttler, who leads the run charts with 629 in this year's IPL, but it was England team-mate Ali who delivered a scintillating performance at the Brabourne Stadium.
The 34-year-old fell in the final over just seven short of a century after a tremendous 57-ball innings that included 13 fours and three sixes.
He then superbly posted figures of 1-21 with the ball from his four-over allocation – but his efforts ultimately proved in vain, with Ashwin's 40 from 23 proving decisive.
Chahal equals spin record
Chahal once again edged ahead of Royal Challengers Bangalore's Wanindu Hasaranga in the battle to be the competition's top wicket-taker.
The Royals' leg-spinner picked up two wickets, while going at just 6.5 an over, and equalled Imran Tahir's tally of 26 (in 2019) for the most wickets by a spinner in a single IPL season.
Fast bowler Richardson played once in the 2021 edition, taking 1-29 from three overs in Bangalore's 10-wicket win over Rajasthan Royals on April 22.
Leg-spinner Zampa, however, did not feature for the Royal Challengers, who confirmed the departure of the duo for personal reasons.
"Adam Zampa and Kane Richardson are returning to Australia for personal reasons and will be unavailable for the remainder of #IPL2021. Royal Challengers Bangalore management respects their decision and offers them complete support," a statement on Twitter read.
Andrew Tye had become the first Australian to depart the IPL bubble on Sunday, a decision made by the Rajasthan Royals fast bowler over concerns about flights home amid a rise in COVID-19 cases in India.
The country has been setting global records for daily figures, with over 17million confirmed cases in total during the pandemic.
"I just thought I should try and get on the front foot and get home before I got locked out of the country," Tye told radio station SEN while in Doha awaiting to complete his journey to Australia.
"There's definitely concerns. A lot of guys have been in touch once they've realised I was leaving. Some of the guys are very interested in what route I took home and how I approached it."
A three-day snap lockdown was placed on the Perth and Peel areas of Western Australia last week amid concerns over coronavirus spreading within communities.
Ashwin, meanwhile, is leaving the Delhi Capitals squad to focus on helping his family during the coronavirus crisis.
"I would be taking a break from this year's IPL from tomorrow," he tweeted on Sunday. "My family and extended family are putting up a fight against COVID-19 and I want to support them during these tough times. I expect to return to play if things go in the right direction. Thank you."
Ashwin has taken one wicket and posted an economy rate of 7.73 runs per over in his five outings for the Capitals, who defeated Sunrisers Hyderabad on Sunday to make it four wins in five outings.
The New Zealand skipper scored just 216 runs from 13 innings at an average of 19.64 in the IPL this year.
Sunrisers on Tuesday announced that Williamson has not been retained by the franchise, who finished eighth last season.
Nicholas Pooran and Sean Abbott are among the other players who have not been kept on by Hyderabad.
It was also the end of an era for Mumbai Indians, with Kieron Pollard calling time on his IPL playing days and taking over as the franchise's batting coach.
Kolkata Knight Riders will have to do without Pat Cummins, Alex Hales and Sam Billings after the overseas trio opted out of the 2023 tournament.
Dwayne Bravo and Chris Jordan were among the players on the Chennai Super Kings' list of released players, while Jason Holder will not feature for Lucknow Super Giants.
Black Caps duo Daryl Mitchell and Jimmy Neesham will not return to Rajasthan Royals, while the same goes for South Africa batter Rassie Van Der Dussen.
The Royals were beaten by the Titans in the first qualifier, forcing them to face Royal Challengers Bangalore on Friday for a place in the season's showpiece.
Buttler ensured RCB were soundly beaten, smashing an unbeaten 106 off 60 balls to clinch a seven-wicket victory.
The Royals still had 11 balls to spare when Buttler's sixth six completed the job on 161-3.
None of the England star's team-mates had to pass 25 runs as he did all the heavy lifting in partnerships of 61 with Yashasvi Jaiswal, 52 with Sanju Samson, 35 with Devdutt Padikkal and 13 with Shimron Hetmyer in reply to RCB's 157-8.
A stunning Buttler catch had removed the dangerous Rajat Patidar (58) in the outstanding moment of the RCB innings, too, as his almost single-handed pursuit of the title continued.
Buttler blowing away the competition
This has long since been Buttler's best IPL campaign, and there remains a slim chance he also takes the tournament record. In pursuit of Virat Kohli's 973 runs in 2016, he moved on to 824 for this tournament with his fourth century. The rest of the players in this year's IPL have produced only four hundreds between them.
As well as the most runs in the 2022 IPL, Buttler leads the way for fours (78, 26 clear of second place) and sixes (45, 11 clear).
Top two tussle once again
This will be the Royals' first final since the inaugural IPL in 2008, when they took the title, but Rajasthan will have their work cut out against a Titans side who are in their debut season.
Gujarat finished two points ahead of the second-placed Royals in the points table, having won the match between the pair by 37 runs. The margin in the subsequent qualifier was seven wickets. Buttler top-scored for Rajasthan on both occasions, but their opponents have collectively shown they have the firepower to match him.
The English opener cracked 116 from 65 balls in Rajasthan's 222-2, making his highest score of the IPL campaign so far and emphasising his position as the leading run-scorer in the 2022 competition. Despite a late rally, Delhi fell short by making 207-8 in reply, sliding to a 15-run defeat, with the Royals going top of the table.
This was game seven for the Royals and Buttler, and he came up trumps once more, sharing in a first-wicket partnership of 155 with Devdutt Padikkal (54) before captain Sanju Samson (46no) came out firing for the final overs.
Delhi were up against it from the off but had a sniff of a chance when Rishabh Pant began finding all corners of the Wankhede Stadium; however, Pant's departure for 44 from 24 balls in the 12th over meant there was only tenuous hope left.
Prithvi Shaw (37) and David Warner (28) had given Delhi a reasonable enough start but failed to stick around.
Yuzvendra Chahal at deep fine leg dropped Pant early in the 12th over, misreading the flight of the ball, but the batsman fell two deliveries later. Pant got a top edge when looking to pull into the leg side, and Padikkal watched the ball soar high into the night sky before it fell to allow him to take a fine catch.
Lalit Yadav and Rovman Powell showed fight to leave Delhi needing 36 from the final two overs, but Prasidh Krishna (3-22) then had Yadav caught behind in a remarkable wicket maiden. Three sixes by Powell at the start of the 20th over raised hopes of a miracle finale, but Delhi's protests over a possible no-ball killed their own momentum.
Buttler serves up another ton of treats
Man-of-the-moment Buttler came into this season with one century in 65 IPL matches, spread across six years. Now he has four in 72, and on this occasion it took him 36 balls to reach 50 and only 21 more to advance to three figures.
Buttler made a ton against Mumbai Indians in his second game of the season, and followed that knock of exactly 100 with an impressive 103 in his sixth outing, against Kolkata Knight Riders. There were nine fours and nine sixes in this masterpiece by the 31-year-old, and he has 491 runs for the season, 226 more than the next highest scorer in the competition (KL Rahul – 265).
Surreal McCoy
Royals paceman Obed McCoy cost his team 26 runs with a dreadful over that included nine runs given away in extras, five of which came from a wild and head-high no ball that raced away to the boundary. It was probably the worst delivery that will be bowled in this year's IPL, sailing way outside off stump after slipping out of McCoy's hand and landing several yards wide of wicketkeeper Samson.
When McCoy conceded three sixes from the first three balls of the final over, Delhi needed three more maximums for victory, but the paceman avoided further embarrassment.
Suryakumar Yadav scored 79 not out from 47 balls as the Indians, who won the toss and elected to bat, set a strong total of 193-4 in Abu Dhabi.
Jos Buttler smashed 70 from 44 deliveries in response but he lacked meaningful support from any of his Royals team-mates, who will be eagerly anticipating the availability of Ben Stokes once his period of quarantine in the United Arab Emirates is over.
Jasprit Bumrah starred for the Indians with bowling figures of 4-20 – his best in the IPL – to ensure his team moved above the Delhi Capitals at the summit and condemned the Royals, who had won their first two matches, to a third consecutive defeat as they were bowled out for 136.
YADAV GOES BIG
After opener Quinton de Kock fell to IPL debutant Kartik Tyagi, Mumbai looked like they could be in trouble in their middle overs when Shreyas Gopal (2-28) removed Rohit Sharma (35) and Ishan Kishan (0) with successive deliveries.
Krunal Pandya went to Jofra Archer for 12 but Yadav pushed the Indians forward, bringing up his fifty with a four off Tom Curran.
Yadav established an unbeaten partnership worth 76 runs with Hardik Pandya (30 off 19) and finished with 11 fours and a pair of maximums for his highest IPL score.
POLLARD DENIES BRILLIANT BUTTLER
The Royals' hopes of being competitive were effectively dashed inside their opening three overs as they lost Yashasvi Jaiswal and Sanju Samson to Trent Boult for ducks either side of Steve Smith swiping Bumrah to De Kock.
Rajasthan were in poor shape at 12-3 – the third game in a row they have been three down inside seven overs – but Buttler launched five maximums and found the rope four more times to give them hope.
However, a stunning catch from Kieron Pollard, who adjusted well in the deep after Buttler's shot initially hit his forearm, ended the wicketkeeper-batsman's electric knock.
Bumrah capped a commanding display from the Indians by dismissing Rahul Tewatia (5) and Gopal (1) in the same over before accounting for Archer at the end of his next set of six.
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.
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.
In their previous encounter, a 15-run loss to Rajasthan Royals on Friday, the team was left incensed by what they believe was a missed no-ball call in the final over. Needing an improbable 36 off the final over, Powell kept things interesting when he blasted three straight 6s off international team Obed Mccoy.
The Capitals were convinced the third six was also a waist-high no-ball and as such would have been a free hit, which would have made things even more interesting. The delivery was, however, not called by the umpires and Mccoy fought back to dismiss Powell. The incident led to arguments between Delhi players and the umpire, and assistant coach Rajasthan Royals Pravin Amre came onto the field. In the aftermath, Delhi Capitals captain Rishabh Pant, all-rounder Shardul Thakur and Amre were slapped with heavy fines resulting from the incident, with Amre also given a one-match ban. With a match upcoming against the Kolkata Knightriders on Wednesday, Powell is looking to move past the incident.
“It’s something that we have to put behind us and put behind us very fast. We have a lot of upcoming matches and we have no time to sit down and dwell in the past,” Powell said of the incident.
“We have some important games coming up, important games that we have to win to get to the next round of the competition,” he added.
“We are about 6th or 7th in the table that is a good place to be. It’s just for us to climb the ladder and hopefully, we’ll reach our goal, which is the top four.”
The latest edition of the IPL was due to begin on March 29, but the Board of Control for Cricket in India pushed the start date back due to the coronavirus pandemic.
Wicketkeeper-batsman Buttler, who was part of the England squad who flew home early from Sri Lanka due to the COVID-19 outbreak, is due to play for Rajasthan Royals once again.
Appearing on a Sky Sports podcast with former internationals Rob Key, Nasser Hussain and Michael Atherton, the 29-year-old revealed he is yet to hear when - or indeed if - the tournament will start, but is optimistic even a shortened campaign may be possible this year.
"Nothing really at the moment," he replied when asked by Hussain if he was aware of any further updates on the situation.
"We saw that initially that it is going to be postponed until April 15, but at the moment everything seems very indefinite. It's hard to see this changing in the immediate future, so I don't see that as a possibility.
"But, as we know, things can hopefully change for the positive as well.
"That's such a massive tournament for world cricket, so hopefully there becomes a situation where some of it – or a shortened tournament – can go ahead."
England's tour of Sri Lanka was cut short midway through a warm-up fixture ahead of the first of two Tests against their hosts.
Buttler and his team-mates are now at home instead, though the 29-year-old is capitalising on some unexpected time off during his busy schedule.
"For me, actually, I'm just trying to make the most of this time and give myself a bit of a break, a mental break, and enjoy some time at home," he said.
The International Cricket Council (ICC) last week stated it is still planning for the World Cup to start in Australia on October 18, but other options are being explored due to the coronavirus pandemic.
It has been reported that the competition will be put back to next year, with the IPL - which could not get under way as scheduled in March - taking place instead of the global event.
Smith, who returned to training with New South Wales on Monday, would prefer to play in a World Cup, but the former Australia captain would also relish the opportunity to lead the Rajasthan Royals later this year.
The top-ranked Test batsman in the world said: "I think when you're playing for your country at a World Cup, that's the pinnacle for one-day or T20 cricket, so of course I'd prefer to play in that.
"But if that doesn't happen and the IPL's there, and they postpone [the T20 World Cup], then so be it. IPL's also a terrific tournament as a domestic tournament.
"That's out of everyone's control at the moment, players are just doing what we're told and going where we need to go and playing whatever's on at that stage.
"I guess there'll be some more news about it soon, probably some decisions to be made soon, so I'm sure we'll all find out and know where we're going to be.
"I personally haven't really thought about it, I think it'd just be going off the advice of the professionals and the governments and essentially doing what we're told.
"If that happens then great, if not then there's just so much going on in the world right now that cricket kind of seems a little bit irrelevant. So, we'll get back when we're told to and until then it's sit tight, get fit and strong and freshen up mentally."
Cricket Australia are also considering a request from the England and Wales Cricket Board to tour England for a limited-overs series in September, two months later than planned.
