Grigor Dimitrov produced the upset of the 2021 Indian Wells tournament on Wednesday, beating top seed Daniil Medvedev from a set and a double-break down.
Trailing 6-4 4-1, Dimitrov won eight straight games to take control of the match against the wayward US Open champion before winning 4-6 6-4 6-3.
Already enjoying his best ever showing in the Californian desert, Dimitrov is through to his first ATP Masters quarterfinal of the season and will next play No.8 seed Hubert Hurkacz.
Hurkacz swatted aside Aslan Karatsev 6-1 6-3 and remains on track for a version of the 'Sunshine Double' after winning the Miami Open six months ago.
On Wednesday evening, second and third seeds Stefanos Tsitsipas and Alexander Zverev booked their quarterfinal spots with wins over Alex de Minaur and Gael Monfils respectively.
Azarenka, Ostapenko set blockbuster semifinal
As all eight men's fourth-round matches unfolded, two women's quarterfinals also featured on the schedule.
The first saw two-time Australian Open champion Victoria Azarenka end the run of in-form American Jessica Pegula, with Azarenka's 6-4 6-2 win sending her through to just her third, and biggest, semifinal of 2021.
"I thought it was a really good match. Very consistent in terms of level for me," said Azarenka, who fell to Pegula in the opening round of AO 2021.
"I felt that I really played well in the crucial moments. I felt like I stepped up a lot to the occasion. That's what I'm really happy with today."
The former world No.1 will need to step up to the occasion again in the semifinals when she faces 2017 Roland Garros champion Jelena Ostapenko for the first time.
Ostapenko won a dramatic final set against American Shelby Rogers, missing a simple overhead putaway, which would have given her a 2-0 lead, before falling behind 1-3, 0-40.
Yet from there, she played characteristically aggressive, fearless tennis to complete a 6-4 4-6 6-3 win.
"I raised my level. I think from 1-3 down, 0-40, I played like a top player," said Ostapenko, who is through to her biggest semifinal since Wimbledon more than three years ago.
Dimitrov scores biggest win since 2016
Earlier on Wednesday, Medvedev’s first serve deserted him as Dimitrov began his comeback from 4-1 down in the second set.
He landed less than 30 per cent of first serves in that set as his game and confidence seemed to fall away.
Dimitrov showed a superior ability to hit through the slow hard court and also, notably, won the majority of longer rallies against Medvedev, highly regarded for his defensive skills.
Dimitrov surged to a 5-1 third-set lead and unleashed a flurry of forehand winners when he served for the match on his second attempt.
"I'm really trying to be appreciative of the moments that I get to be out here on the court and stay humble, and work. And think that's the only thing that you can do, and control,” said Dimitrov.
"At the moment I just have a lot of gratitude towards my game, towards my team, towards my work, and the effort that I'm putting in.
"So I think when you put that all together, you start to enjoy the game a little bit more, and winning and losing seems to not have such a big pressure.”
Medvedev’s nine-match winning streak ends; he had not lost since falling to Andrey Rublev in the Cincinnati semifinals in August.
The world No.2 is the highest-ranked player Dimitrov has beaten in five-and-a-half years, dating back to when he upstaged second-ranked Andy Murray in the third round of the 2016 Miami Open.
It was also the first time he had beaten Medvedev in more than four years, with the Russian winning their past three encounters without dropping a set.
This is Dimitrov’s second straight tournament quarterfinal; he advanced to the semifinals in San Diego two weeks ago and has won six of his last seven matches.
In other results, Diego Schwartzman upset in-form sixth seed Casper Ruud 6-3 6-3 and will play Brit Cameron Norrie, who sealed his place in the quarterfinals after a three-set win over Tommy Paul.
Local star Taylor Fritz backed up his win over Italian No.1 Matteo Berrettini, winning eight straight games from 4-2 down in the first set against Italian No.2 Jannik Sinner before winning 6-4 6-3.
Also moving through to the quarters was 29th seed Nikoloz Basilashvili; he stopped Olympic silver medallist Karen Khachanov 6-4 7-6(6) and will next play Tsitsipas, who fended off a resurgent De Minaur in a high-quality clash to eventually triumph 6-7(3) 7-6(3) 6-2.
In the last match of the day, Zverev comfortably saw off 14th seed Monfils and will face Fritz having won 19 of his past 20 matches.