Top seed Carlos Alcaraz has been defeated in the last 16 of the Shanghai Masters by Grigor Dimitrov.
World number two Alcaraz, 20, won three games in a row to take the first set, but Dimitrov fought back to win 5-7 6-2 6-4.
Bulgarian Dimitrov, who is seeded 18th, will face Chilean 22nd seed Nicolas Jarry in the quarter-finals on Friday.
The 32-year-old is looking to secure his first ATP title since winning the season-ending championship in 2017.
“I’m still here, I’m not going anywhere,” said Dimitrov after the match.
Jarry, 28, booked his place in the last eight of the tournament – the first Shanghai Masters since the Covid pandemic – with a 6-3 5-7 6-3 victory against Argentina’s Diego Schwartzman.
Wimbledon champion Alcaraz has beaten Dimitrov on three separate occasions and was chasing his seventh tour title of the season in China.
But the Spaniard was out of sorts despite winning the opening set in just under an hour and was broken twice by Dimitrov in the second set.
In the deciding set, Alcaraz’s serve was broken again in the third game after another unforced error, leading the two-time Grand Slam winner to let out a roar of anger.
“In the third set it was a bit cat and mouse,” added Dimitrov. “I knew I had to apply constant pressure on him.”
In the other quarter-finals, Frenchman Ugo Humbert needed just 57 minutes to defeat American JJ Wolf 6-2 6-2, while Russian 12th seed Andrey Rublev faces Tommy Paul of the US in the night session.
Also on Wednesday, organisers of the Japan Open announced Britain’s Andy Murray and home player Kei Nishikori will not play in next week’s tournament because of injury.
In a statement, Nishikori said: “It’s very difficult not being able to play in front of the Japanese fans, but I’m still not back to 100% and am continuing to train to get back on tour.”