Holger Rune rallied from a set down and saved a match point to defeat former champion Taylor Fritz 2-6 7-6(2) 6-3 on Wednesday and reach the Indian Wells quarter-finals where he will meet fourth seed Daniil Medvedev.
Rune surrendered the opening set in 32 minutes and looked down for the count when 2022 winner Fritz went up 5-4 and 40-30 in the next, but the seventh-seeded Dane produced a vital hold before forcing a tiebreak.
The 20-year-old stepped up a gear to level the contest at one set all and broke his American opponent for the first time with some blistering shotmaking for a 3-1 lead in the decider.
With Fritz wilting in the California desert, Rune completed the comeback by closing out the match on serve, finishing with a fiery forehand winner.
"It was crazy. I really just stayed in the moment and kept fighting, trying to play better point to point and I managed to raise my level quite amazingly at the end of the second set, which meant everything for the match," Rune said.
"He was controlling it in the first set and for a long time in the second as well, so I'm just happy I could keep fighting. I kept believing I was going to find my rhythm at some point. It was on the edge but I managed to find it, which was nice."
Up next for Rune is last year's runner-up Medvedev, who outclassed Grigor Dimitrov 6-4 6-4 with a near-flawless display to stay on course for his first title of the year after falling in the Australian Open final.
Rune, who split his two career meetings with the Russian last year, said he would come out all guns blazing.
"I'm a player that's going to attack. I don't care who I play, I'm going to attack anyways," Rune said.
"Against Daniil it's a completely different match from today. The only similarity between him and Fritz have is the big serve. Fritz is close to the baseline while Medvedev is far.
"Medvedev on this surface is dangerous like Fritz. I'm just going to recover and believe in myself like I did today."
Earlier, Casper Ruud ended Frenchman Gael Monfils's run with a 3-6 7-6(3) 6-4 victory and plays Tommy Paul after the American brought lucky loser Luca Nardi back down to Earth.
After struggling to put winners past the athletic Monfils in the first set, the Norwegian ninth seed became more aggressive in a tight second and rolled through the tiebreak.
Ruud finally broke his 37-year-old opponent for a 3-1 lead in the deciding set and cruised to the finish.
A nice moment came when Monfils walked to the service line trailing 3-5 in the third and the crowd rose to cheer on the fan favourite, who smiled and waved his racket in appreciation before holding serve.
After stunning his idol Novak Djokovic on Monday, 20-year-old Italian Nardi was served a dose of reality by Paul, who hit five aces and never dropped serve en route to a 6-4 6-3 win.
Navarro stuns Sabalenka, Gauff cruises into quarters
American Emma Navarro stunned world number two Aryna Sabalenka 6-3 3-6 6-2 to record the biggest win of her career and reach the Indian Wells quarter-finals for the first time on Wednesday while Coco Gauff celebrated her birthday by advancing with ease.
Navarro absorbed Sabalenka's powerful serve and converted four of her five break-point opportunities to beat the reigning two-time Australian Open champion in windy conditions.
Navarro came out flying to grab the first set before Sabalenka raised her level in the second to force a decider.
The even-keeled Navarro kept her cool, fending off a break point and smacking a forehand winner for a crucial service hold and a 4-1 lead.
Navarro, seeded 23rd, broke the hard-hitting Belarusian for a fourth time on match point to book a quarter-final clash with ninth seed Maria Sakkari of Greece.
Sakkari, the 2022 runner-up, beat Frenchwoman Diane Parry 6-2 3-6 6-3.
Navarro, who is known for keeping her emotions under wraps, did a subdued fist pump after winning the match in front of a supportive crowd at Stadium One.
"It's a little bit unnatural for me to be in the spotlight and be playing on a court like that with a ton of fans and TVs and eyes on me. It's not my natural way," she told reporters.
"But I feel I'm definitely getting more comfortable with it and just feeling like I can be myself even if there's however many people watching.
"Also I think that was my second or third fist pump ever. If it was a little weird, cut me some slack," she said with a smile.
With the win Navarro will break into the top 20 for the first time after the tournament and Sabalenka, who won her second Grand Slam crown in Melbourne Park in January, praised her opponent.
"Her potential is really great," Sabalenka told reporters.
"I think she has the potential to be in the top 10."
Gauff dominated Elise Mertens to win 6-0 6-2 on her 20th birthday and book her spot in the quarter-finals.
The dynamic American played her best tennis of the tournament so far, serving well and stepping into the court to overwhelm the Belgian 24th seed.
Mertens was unable to back up her win over Naomi Osaka in the previous round, hitting just four winners to 21 unforced errors in a match that lasted just over an hour.
Third seed Gauff saw her section of the draw open up after Sabalenka's defeat and will play unseeded Yuan Yue of China, who fought back from a set and a break down to beat Russian 11th seed Daria Kasatkina 4-6 6-4 6-3.
Yuan, who claimed her first WTA title in Texas this month, stunned compatriot and Australian Open runner-up Zheng Qinwen in the second round and will look for another upset to extend her nine-match winning run.
