Three-time grand slam champion Murray had rolled back the years to reach his first ATP Tour championship match since beating Stan Wawrinka in Antwerp back in October 2019.
There was to be no 47th ATP Tour singles title for the Briton at Ken Rosewall Arena, though, as Karatsev won 6-3 6-3 to ensure he will start the Australian Open next week with a spring in his step.
The world number 20 from Russia was a surprise semi-finalist in the first grand slam of the year at Melbourne Park last year and looks capable of making his presence felt again.
Karatsev struck 27 winners to 13 from the racket of former world number one Murray, who was unable to break the Vladikavkaz native's serve.
Murray failed to hold in the first game of the final and the opening set was over when he was broken for a second time.
Karatsev surged into a 3-0 lead in the second set and fended off five break points before finally holding to take a 4-1 lead, then went on to serve it out as he secured a third ATP Tour singles title, having been triumphant in Moscow and Dubai last year.
Murray will take great heart from the strides he has made this week and three years after fearing he may be force to retire at the Australian Open, the 34-year-old will face Nikoloz Basilashvili in the first round of the 2022 tournament next week.
Karatsev will do battle with Spaniard Jaume Munar for a place in the second round at Melbourne Park.
Mannarino secured a 7-6 (9-7) 6-4 win on Sunday to reach the second round in his homeland.
The Frenchman roared back from 5-1 down in the first set and rocked Karatsev further by winning the tie-break.
Mannarino then claimed the only break of the second set to advance at the expense of the Russian.
Holger Rune will be his opponent in round two following the Dane's 7-6 (7-4) 7-6 (7-3) defeat of Arthur Rinderknech.
Francisco Cerundolo will do battle with top seed Cameron Norrie in the second round after the Argentine saw off James Duckworth 6-2 3-6 6-3.
There were just two matches in the first round of the Geneva Open, with Tallon Griekspoor and Kamil Majchrzak progressing at the expense of seeds Tommy Paul (6) and Alexander Bublik (8) respectively.
World number one Medvedev fought back from a set down to defeat Aslan Karatsev 3-6 6-4 6-2 and advance to a quarter-final against fifth seed Roberto Bautista Agut, who was granted a walkover after Nick Kyrgios pulled out with an abdominal issue.
The Russian got just 48 per cent of his first serves in during a blustery opening set before improving to 68 per cent in the second and controlling the decider as Karatsev struggled with injury.
"It was tough to play [in] rhythm. It felt like many points were just whoever managed to put the ball in the court was going to win the point," Medvedev said of the tricky conditions.
"It was not easy but I'm happy to win because that's the most important [thing].
"Last year was amazing. I played great tennis. Hopefully I can do the same this year. I like it here in Mallorca, so hopefully I can stay as long as possible in the tournament."
Alongside Medvedev and Bautista Agut, Stefanos Tsitsipas is the only other seed left in the draw after he overcame Ilya Ivashka 6-4 6-4.
Denis Shapovalov was a 6-4 6-1 loser against Benjamin Bonzi, Pablo Carreno Busta went down 6-3 6-4 to Antoine Bellier and Sebastian Baez's meeting with Daniel Altmaier ended in a 6-2 2-6 6-4 defeat for the Argentine.
At the Eastbourne International, second seed Sinner suffered a 6-3 3-6 6-3 loss to Tommy Paul as he made his return from a knee injury sustained at the French Open.
World number 13 Sinner remains without a grass-court win in his ATP Tour career, while Paul will next face defending champion Alex de Minaur, who overcame Lorenzo Sonego 7-6 (7-3) 6-2 in a repeat of last year's final.
Jack Draper defeated fourth seed Diego Schwartzman 7-5 7-6 (7-3) to advance to the quarter-finals and Cameron Norrie cruised past Brandon Nakashima in straight sets.
There were also wins for Maxime Cressy, Alexander Bublik and Taylor Fritz.
Blocking Murray's way to a first ATP Tour title since October 2019 will be Russian player Aslan Karatsev, whose gritty win over Dan Evans prevented an all-British final.
Evans won a marathon tie-break in the second set of that encounter but could not maintain the level as he lost out 6-3 6-7 (13-15) 6-3 to a player who caused a sensation by reaching the 2021 Australian Open semi-finals.
It was also a case of digging deep for Murray, who picked up a stellar win over American Reilly Opelka, triumphing 6-7 (6-8) 6-4 6-4 against the fourth seed and world number 25. Murray is ranked down at number 135, but this strong week has provided evidence he still belongs at a much higher level.
Three years have passed since Murray came to Australia and indicated he was close to retirement due to hip trouble. He has battled back against the odds to stay active, but his lone ATP singles final appearance since that point came at the 2019 European Open in Antwerp, where he beat Stan Wawrinka to land a surprise title.
Now he is back in another title match, for what will be just his fourth singles final on the main tour since the end of the 2016 season, when he reached world number one status.
Murray rifled 16 aces and no double faults, winning an impressive 88 per cent of points when he landed his first ball in court, and his serve was not broken at any point by Opelka.
He has 46 singles titles and dearly wants to reach 50 before calling it a day, with a glorious chance to land a 47th coming up on Saturday.
Karatsev, the world number 20, is not a player that Murray would underestimate. He was ranked 114th and largely unknown before going on his run to the final four in Melbourne last February, but he has since pushed on and should provide a stiff test for three-time major winner Murray.
"It's already been a great week for me, big progress from anything I've done in the last year or so, to string four matches together like this and against top players in Basilashvili and Opelka," said Murray. "I'll go for 47 tomorrow. It's been a good week, I've played better with each match, so hopefully I'll step it up again."
At the Adelaide International 2 event, Australian wildcard Thanasi Kokkinakis produced a stunning semi-final win over fourth seed Marin Cilic, battling to a 6-2 3-6 7-6 (12-10) victory over the former US Open champion, teeing up a shot at Frenchman Arthur Rinderknech in the title match.
The 20-year-old American, who took a set off Novak Djokovic and rattled the world number one at the US Open, is shaping up as potentially his country's biggest hope for the future in the men's game.
Californian Brooksby crushed Spain's world number 44 Alejandro Davidovich Fokina 7-5 6-0, and second seed Schwartzman awaits after the Argentinian took down another 20-year-old American, Brandon Nakashima, scoring a 6-4 6-2 quarter-final win.
Schwartzman is the man who ended Andy Murray's hopes at the tournament in Antwerp.
Brooksby, who had to win two qualifying matches to reach the main draw, said: "Tomorrow will be a great match. I'm really looking forward to it. I'll get some rest tonight and get ready to battle again tomorrow."
The other semi-final will see Italian top seed Jannik Sinner take on South African seventh seed Lloyd Harris following their respective straight-sets wins over Arthur Rinderknech and Marton Fucsovics.
There will be an all-Russian semi-final at the Kremlin Cup in Moscow, after Aslan Karatsev and Karen Khachanov won through to the final four.
Second seed Karatsev sank the hopes of Frenchman Gilles Simon, breaking serve five times on the way to a 6-4 6-3 win, while third-seeded Khachanov edged out Australian John Millman. A 7-5 7-6 (7-4) grind featured 19 aces by Khachanov, the 2018 Kremlin Cup champion, who saved four set points in the second set.
Marin Cilic thrashed Pedro Martinez 6-1 6-2 to set up a tussle with Ricardas Berankis, the Lithuanian ending Adrian Mannarino's run with a 6-2 7-6 (7-1) success. Frenchman Mannarino had stunned Russian top seed Andrey Rublev in the previous round.
Rublev – the world number five – won 6-2 6-1 over local 20-year-old Nakashima at the ATP 250 tournament on Wednesday.
Nakashima claimed only two of 18 second serve points for the match, with Rublev breaking him six times and triumphing in one hour, two minutes midweek.
The result improves 2021 Australian Open quarter-finalist Rublev's record to 45-15 this calendar year.
Rublev will take on sixth seed Diego Schwartzman, who rallied to defeat Lloyd Harris 4-6 6-3 6-2 in San Diego.
Fifth seed Hubert Hurkacz moved into the next round with a 7-6 (7-2) 6-1 victory over Australian qualifier Alex Bolt.
Hurkacz will face Russian and 2021 Australian Open semi-finalist Aslan Karatsev in the round of 16.
Daniel Evans – the eighth seed – overcame former Wimbledon and US Open runner-up Kevin Anderson 7-6 (13-11) 7-5 after more than two hours on court.
Evans will meet countryman Cam Norrie next.
The fifth seed found a crucial break of serve when leading the opener 5-4 to take the first set in Kazakhstan, before winning the next three games to put himself in the ascendancy in the second.
And despite a desperate last stand to stay in the match from Djere, Rublev held serve three times with relative ease to finish off his Serbian opponent.
Eighth seed Felix Auger-Aliassime served 14 aces to Roberto Bautista-Agut's two in their first-round match, but it was the Spaniard who advanced with a 6-4 7-6 (8-6) success.
Meanwhile, world number 10 Hubert Hurkacz overcame Francisco Cerundolo in straight sets.
Adrian Mannarino, the runner-up in Astana in 2020, came from a set down to beat Stan Wawrinka – playing as a wildcard – 1-6 6-2 6-3, and qualifier Zhizhen Zhang romped to victory with a superb third set to seal a 4-6 6-4 6-1 comeback win of his own over Aslan Karatsev.
At the Tokyo Open, fourth seed Frances Tiafoe cruised into the second round with a 6-3 6-4 triumph over Yasutaka Uchiyama, one of three Japanese players who crashed out at the first-round stage of their home tournament.
Uchiyama's countrymen Taro Daniel and Shintaro Mochizuki also tasted defeat at the hands of Bernabe Zapata Miralles and Brandon Nakashima, respectively.
Top seed Rublev won 6-1 7-5 in one hour and 52 minutes over the Argentine, who kept on coming throughout the contest.
The Russian world number five's victory books his spot in the last four where he will face Briton Cameron Norrie, who upset fourth seed Denis Shapovalov 6-3 6-1.
Rublev is featuring in his eighth semi-final of the calendar year and chasing his first title since winning in Rotterdam in February.
He had been a break up in the second set after dominating the first, but Schwartzman broke back.
The second set appeared destined for a tie-break with Schwartzman up 40-0 on serve at 5-6, before Rublev won the next five points to claim victory.
"The second set was very tough and enjoyable for the spectators to watch," Rublev said. "Every game was really tough with amazing points and the set could have gone either way."
Second seed Casper Ruud defeated Lorenzo Sonego 6-1 6-4 to book his semi-final spot where he will meet Grigor Dimitrov who beat Aslan Karatsev in three sets.
Ruud's win improved his 2021 record to 45-12, with the 22-year-old Norwegian rising to a ranking of 10.
Top seed Rublev won 6-1 7-5 in one hour and 52 minutes over the Argentine, who kept on coming throughout the contest.
The Russian world number five's victory books his spot in the last four where he will face Briton Cameron Norrie, who upset fourth seed Denis Shapovalov 6-3 6-1.
Rublev is featuring in his eighth semi-final of the calendar year and chasing his first title since winning in Rotterdam in February.
He had been a break up in the second set after dominating the first, but Schwartzman broke back.
The second set appeared destined for a tie-break with Schwartzman up 40-0 on serve at 5-6, before Rublev won the next five points to claim victory.
"The second set was very tough and enjoyable for the spectators to watch," Rublev said. "Every game was really tough with amazing points and the set could have gone either way."
Second seed Casper Ruud defeated Lorenzo Sonego 6-1 6-4 to book his semi-final spot where he will meet Grigor Dimitrov who beat Aslan Karatsev in three sets.
Ruud's win improved his 2021 record to 45-12, with the 22-year-old Norwegian rising to a ranking of 10.
Rublev had won 23 consecutive matches at this level, second only to Roger Federer (28), but Karatsev finally ended the Russian's remarkable run to progress to his first ATP singles final.
Karatsev, who incredibly went from qualifying to the semi-finals of the Australian Open this year, defeated his compatriot 6-2 4-6 6-4.
He became the first Wild Card to reach the final since Thomas Muster in 1997, doing so by hitting 41 winners and forcing 16 break points – of which he won four – during two hours and 12 minutes on court.
"It was a really tight match [against a] tough opponent," Karatsev said in his on-court interview.
"It was an unbelievable performance [from Andrey]. He didn't lose a match at an ATP 500 in [one year]. Everything was decided in one or two points, I feel happy."
The championship match will be between two first-time Dubai finalists after Lloyd Harris stunned Denis Shapovalov in the other semi-final.
World number 81 Harris, who overcame top seed Dominic Thiem, 14th seed Filip Krajinovic and former US Open finalist Kei Nishikori to reach the last four, came from a set and 4-2 down to defeat world number 12 Shapovalov.
He prevailed 6-7 (5-7) 6-4 7-6 (8-6) to reach a maiden ATP 500 final and become the first qualifier to reach the showpiece in Dubai.
"I don't have many words right now. I am super happy with that win," Harris said on court afterwards.
"Being a set and 2-4 down is mentally and physically a little bit troublesome for me, but I found my best tennis from there. I am just extremely happy with the result right now."
Mannarino ultimately came out on top 5-7 7-6 (7-4) 6-3 but he had to do it the hard way, coming back from match point down to set up a meeting with Ricardas Berankis, who lost only tree games in a 6-2 6-1 win over Federico Coria.
Rublev was never cruising, however, as Mannarino only just fell short in the first set and then took the second to a tiebreak, which he eventually won to turn the tide.
The 33-year-old, who lost to Rublev in the final two years ago, took things up a notch in the decider and did not face a single break point as he got the job done despite the home support.
"The crowd was cheering for Andrey but that is normal," he said after reaching the quarter-finals. "I was happy to play with such a nice atmosphere.
"We have been playing for a long time without fans, so it is nice to enjoy a stadium with crowds now."
Second-seed Aslan Karatsev is now the favourite in Moscow, and the Russian had few issues in a 6-4 6-3 defeat of Egor Gerasimov.
Karatsev will face Gilles Simon next following his 6-3 6-2 win over Mackenzie McDonald, while Pedro Martinez won 6-3 6-4 over Filip Krajinovic to book his passage.
At the European Open in Antwerp, Andy Murray's hopes of winning a first ATP Tour title in two years were ended by number two seed Diego Schwartzman.
The Argentinian trailed 4-1 in the first set but fought back to win 6-4 7-6 (8-6) in his first ever match against the Scot, whose last tour triumph was in Antwerp.
In his on-court interview, Schwartzman said: "It was a pleasure to play against Andy. We had not played before and he is coming back and every week he is playing better and moving better.
"I have a lot of respect because when I grew up playing tennis, I was watching Roger [Federer], Rafa [Nadal], Andy and Novak [Djokovic] and right now playing against him is a pleasure for me."
Seventh seed Lloyd Harris is also into the quarter-finals after a straightforward 6-2 6-3 victory over Jan-Lennard Struff in just 72 minutes, Marton Fucsovics came through 6-7 (5-7) 6-3 6-1 against Roberto Bautista Agut and Brandon Nakashima edged past Henri Laaksonen 7-6 (7-5) 6-7 (5-7) 6-3 to earn the right to face Schwartzman.
Rune – the fifth seed for the tournament in Bulgaria – required two tie-breaks to clinch victory in his first meeting with Van Rijthoven on the ATP Tour, eventually claiming a 7-6 (7-2) 7-6 (8-6) win.
After the match, Rune expressed his relief at avoiding a third set, saying: "I didn't want to go to three sets. If it [had happened], I was going to fight for sure and try to take it in three, but I'm very happy to finish in two."
Meanwhile, eighth seed Oscar Otte beat Dragos Nicolae Madaras 6-3 6-2, and Portugal's Nuno Borges overcame Mirza Basic in three sets to tee up a meeting with defending champion and top seed Jannik Sinner.
In Tel Aviv, seeds Aslan Karatsev and Tallon Griekspoor fell at the first hurdle with three-set reverses to Tomas Martin Etcheverry and Vasek Pospisil, respectively.
Etcheverry rallied after Karatsev took a second-set tie-break in comprehensive fashion to post a 6-2 6-7 (0-7) 6-4 win, while lucky loser Pospisil stunned Griekspoor for a 4-6 7-6 (7-3) 7-5 triumph.
Fifth seed Botic van de Zandschulp fared better, however, dispatching Joao Sousa 6-2 6-3 after producing a top-class display of serving.
The Dutchman will meet Britain's Liam Broady in the next round after he recorded a straight-sets win over Hamad Medjedovic.
World number 10 Ruud prevailed 7-5 6-4 over the three-time grand slam winner, rolling to victory after a shaky start.
Murray broke Ruud in the 22-year-old's second service game of the match, but could not maintain the advantage as Ruud converted five of six break points in the match.
Ruud will face ninth seed Lorenzo Sonego, who defeated Sebastian Korda 6-4 6-3, saving six of seven break points against his own serve while converting all three of his chances on Korda's.
Fourth seed Denis Shapovalov defeated Taylor Fritz 7-6 (9-7) 6-2, saving six set points in the process.
The Canadian moves on to a quarter-final meeting with Cameron Norrie, who downed Daniel Evans 7-6 (7-3) 6-3.
Grigor Dimitrov dominated August Holmgren 6-1 6-1 in 56 minutes, winning 83 per cent of his service points.
Dimitrov next faces Aslan Karatsev, who rallied to upset fifth seed Hubert Hurkacz 5-7 6-4 6-2.
Sinner, the number one seed, moved into his fifth final of the season with a 6-2 6-2 defeat of Lloyd Harris in Antwerp.
The 20-year-old Italian, who is in the hunt for a maiden ATP Finals spot, dominated Harris from the baseline and saved all three break points he faced.
There were only 16 unforced errors from the racket of the composed Sinner, who will be bidding to win his fourth title of the season on Sunday.
Sinner said: "I am very happy to be in the final. I just love playing here and love playing indoors, so hopefully I can play a great match again tomorrow."
Schwartzman ended 20-year-old American Jenson Brooksby's impressive run with a 6-4 6-0 victory.
The Argentinian struck 15 winners and secured five breaks as he marched into the championship match.
Russian second seed Aslan Karatsev will come up against Marin Cilic in his first final on home soil after knocking compatriot Karen Khachanov out of the Kremlin Cup.
Karatsev beat Khachanov 7-6 (9-7) 6-1, while sixth seed Cilic – a two-time winner of the tournament in Moscow – got the better of Ricardas Berankis 6-3 6-4.
The 2020 US Open winner did not face a single break point in his one-sided 6-2 6-0 victory on Monday, reaching the last 16 after 62 minutes.
It is just the second time in the Austrian's career he has lost as few as two games in a completed ATP-level match, having previously done so against Jaroslav Pospisil in 2013 (in a 6-1 6-1 win).
"Especially with the forehand, it was really good for basically the first time [since my injury]," Thiem said afterwards. "I'm very happy about it. This way is right, the direction is right."
Meanwhile, Argentina's Sebastian Baez was forced to retire when a set down to France's Constant Lestienne, and fifth seed Tommy Paul eased past 16-year-old home hope Martin Landaluce in straight sets.
Only one seed was in action at the Firenze Open on Monday, with Aslan Karatsev advancing courtesy of a walkover following an injury to Tallon Griekspoor.
Thiem, a 2019 winner at the tournament in his home country, prevailed 6-4 6-2 in Kitzbuhel.
He will next face compatriot Sebastian Ofner as he seeks a first title since his grand slam breakthrough at the US Open in 2020.
Ofner came from a set down to beat former world number seven Richard Gasquet 1-6 7-5 7-5.
Meanwhile, seventh seed Pedro Martinez saved six out of six break points en route to a 7-6 6-3 victory over Chilean Nicolas Jarry.
At the Croatia Open in Umag, Bernabe Zapata Miralles set up a round of 16 meeting with third seed Holger Rune by beating Croatian Dino Prizmic, who retired when facing a 6-4 3-0 deficit.
Alex Molcan is safely through to the next round after defeating Duje Ajdukovic, while French 23-year-old Corentin Moutet cruised to a straight-sets victory over sixth seed Daniel Altmaier.
World number 84 Ruusuvuori saved a set point in the first-set tie-break on his way to a 7-6 (8-6) 6-4 victory and will now face Ilya Ivashka for a place in the semi-finals.
There was nearly another upset as home hopeful Alexander Bublik, seeded second, had to recover from a set down to overcome Miomir Kecmanovic 2-6 6-3 7-5.
Carlos Taberner awaits Bublik in the next round after the Spaniard beat Egor Gerasimov 5-7 7-6(5) 7-5.
Kwon Soon-woo and James Duckworth saw off Dusan Lajovic and Filip Krajinovic respectively in straight sets to remain a course for glory.
At the Moselle Open in Metz, meanwhile, Gael Monfils took out Philipp Kohlschreiber 7-6(2) 6-4 to reach the quarter-finals on home soil.
Tournament favourite Hubert Hurkacz made light work of 2016 champion Lucas Pouille with a 6-2 6-3 victory to set up a meeting with Andy Murray in the quarter-finals.
Elsewhere on Thursday, German qualifier Peter Gojowczyk proved too strong for Karen Khachanov and will now face Marcos Giron, who upset fourth seed Alex de Minaur.
Greek star Tsitsipas flexed his muscles in a straight-sets win over Damir Dzumhur on Saturday.
Australian Open semi-finalist and Dubai Tennis Championships winner Karatsev enjoyed a victorious Miami debut.
Andrey Rublev, Diego Schwartzman, Denis Shapovalov, Marin Cilic and Milos Raonic also progressed at the ATP 1000 tournament.
TSITSIPAS STAYS HOT
World number five Tsitsipas eased past Dzumhur 6-1 6-4 in his first appearance since losing in last week's Mexican Open final.
Tsitsipas (15-4) became the third player to reach 15 wins this season, the second seed following in the footsteps of Russian duo Rublev (17-3) and Daniil Medvedev (15-2).
"It was a great match, especially against a guy that I probably don't have a good record playing against in the past," said Tsitsipas. "I started the match very strong, breaking him twice and taking a big lead in the score, and I think the things worked out by themselves after that."
Tsitsipas will face Kei Nishikori after the Japanese outlasted Aljaz Bedene 7-6 (8-6) 5-7 6-4.
NO STOPPING KARATSEV
Karatsev's Miami Open debut ended in a 6-4 6-3 win for the 17th-seeded Russian over Mikhail Kukushkin.
Already in the ATP's top 100 and set to keep climbing, Karatsev broke serve four times en route to the next round, where Sebastian Korda awaits after upstaging 10th seed Fabio Fognini 1-6 6-4 6-2.
"Of course it gives me confidence to win my first title, but you arrive here and it’s a different surface and new tournament," said Karatsev, who ended last season ranked 112th before bursting into the top 30 behind his semi-final run at Melbourne Park. "So you try [to think of it] as a new tournament and new place, but of course it gives me a lot of confidence."
Karatsev owns a 13-2 record this year, with his only two losses coming against world number one Novak Djokovic and US Open champion Dominic Thiem.
RUBLEV ROLLS ON
Fourth seed Rublev has proven to be remarkably consistent, highlighted by his crushing 6-1 6-2 rain-interrupted victory against Tennys Sandgren.
Having equalled his previous best run in Miami, Rublev will play 29th seed Marton Fucsovics who took down Thanasi Kokkinakis 7-6 (7-3) 6-7 (4-7) 6-4.
Rublev has won a Tour-leading 17 matches this year.
Elsewhere, fifth seed Schwartzman was a 6-3 6-3 winner against Yasutaka Uchiyama, Shapovalov – the sixth seed – trumped Ilya Ivashka 6-7 (5-7) 6-4 6-4 in a marathon, 12th seed Raonic accounted for Jordan Thompson 6-2 6-1, former US Open winner Cilic surprised 13th seed Christian Garin 3-6 7-5 7-6 (7-5), while 15th seed Alex de Minaur was eliminated.
Greek star and second seed Tsitsipas got the better of 2014 US Open runner-up Kei Nishikori in Miami.
Rublev continued his fine 2021 with a straight-sets demolition of Marton Fucsovics at the ATP 1000 tournament.
In-form Aslan Karatsev, however, bowed out following a surprise loss to Sebastian Korda.
TSITSIPAS HALTS NISHIKORI
Despite a mid-match wobble, Tsitsipas overcame Nishikori 6-3 3-6 6-1 to reach the fourth round.
Former world number four Nishikori forced a deciding set but Tsitsipas withstood the Japanese's comeback.
Tsitsipas, who hit 32 winners, will meet Lorenzo Sonego for a place in the quarter-finals after the 24th seed defeated Daniel Elahi Galan 7-6 (8-6) 6-3.
RUBLEV STAYS HOT
Russian fourth seed Rublev made light work of Fucsovics 6-2 6-1 in just 52 minutes.
Rublev leads the ATP Tour with 18 victories this season after eliminating the in-form Hungarian, ahead of top seed Daniil Medvedev (16-2).
The result secured a third win for Rublev over 29th seed Fucsovics this month.
"I was laughing, because of [the] situation and plus Marton also told me, 'I don't want to see you. I don't want to see you'," Rublev said, cracking a laugh. "[It was] just a situation that [was] fun, and I feel sorry."
Awaiting Rublev is 2014 US Open champion and former world number three Marin Cilic, who beat Lorenzo Musetti 6-3 6-4.
KARATSEV CONQUERED
For only the third time this year, Australian Open semi-finalist and Dubai Tennis Championships winner Karatsev tasted defeat following a 6-3 6-0 loss at the hands of Korda.
American sensation Korda became the first player outside the top five to beat Karatsev this year, with the latter's previous two losses coming against world number one Novak Djokovic and world number four Dominic Thiem.
"It is super special [to reach the Round of 16], especially playing a guy who was as hot as he was," said Korda. "I just took the tactics that I used [against him] at Roland Garros and it worked out really well today."
Diego Schwartzman stands in the way of Korda and the quarters after the fifth seed accounted for Adrian Mannarino 6-1 6-4.
Elsewhere, Denis Shapovalov – the sixth seed – was upstaged by Hubert Hurkacz 6-3 7-6 (8-6).
Another Canadian awaits Hurkacz after 12th seed Milos Raonic was a 6-4 7-5 winner against Ugo Humbert.
Medvedev – the US Open champion – has lost only three of his last 41 sets, and has never dropped one to McDonald in five career meetings with the American as he maintained his red-hot form.
Russian star Medvedev is now 37-5 on hardcourts this year and appears well-positioned to make it past the third round of the ATP Masters 1000 tournament for the first time as he awaits Filip Krajinovic.
"I'm actually really pleased, because usually I haven’t played well in Indian Wells and I haven’t been playing that well in practices before [the tournament]," Medvedev said in his on-court interview. "[I am] really happy with my performance. That’s the most important [thing] no matter how I played before the tournament."
RUBLEV ROLLS PAST TABERNER
Medvedev's countryman Andrey Rublev closed out the night session with a 6-3 6-4 defeat of Carlos Taberner, who was facing a top-10 opponent for the first time.
Fourth seed and world number five Rublev won 66 per cent of points on his first serve and hit 30 winners to Taberner's 12.
Rublev improved to 47-16 this season, 31-9 on hard courts, and will face Tommy Paul in the third round.
SHAPOVALOV WINS IN NEAR-WALKOVER
Most of the seeded players in action had an easy time of it, none more so than Canadian ninth seed Denis Shapovalov.
Shapovalov's opponent and countryman Vasek Pospisil retired with an apparent back injury after dropping the first three games of the match.
Sixth seed Casper Ruud blew past Roberto Carballes Baena 6-1 6-2, while eighth seed Hubert Hurkacz downed Alexei Popyrin 6-1 7-5.
Diego Schwartzman had to work harder to advance, the 11th seed outlasting qualifier Maxime Cressy 6-2 3-6 7-5.
Top-ranked American Reilly Opelka, the 16th seed, beat Taro Daniel 7-5 6-3 for his first main-draw victory at Indian Wells in four attempts.
Daniel Evans also went the distance to defeat Kei Nishikori 4-6 6-3 6-4, while former world number three Grigor Dimitrov, 2021 Australian Open semi-finalist Aslan Karatsev and Frances Tiafoe were among the other players to advance.
