Novak Djokovic was knocked out of the Monte Carlo Masters by an inspired Dominic Thiem in the third round on Thursday, with the Austrian fifth seed progressing to a possible quarter-final with Rafael Nadal.
Thiem, a two-time French Open semi-finalist, was the better player for much of the match and won 6-7 (2/7), 6-2, 6-3 despite a battling effort from Djokovic.
The 12-time Grand Slam champion has still not reached a quarter-final since Wimbledon last July after struggling with an elbow injury.
Djokovic, 30, had said he was pain-free in Monte Carlo for the first time in two years, but Thiem backed up his French Open quarter-final win over the Serbian from last year with another impressive victory.
The 24-year-old will take on either world number one Nadal or Russian Karen Khachanov in the quarter-finals.
World number seven Thiem laid down a marker in the opening stages, holding to love before breaking the Djokovic serve with a clean forehand winner.
Djokovic faced a set point on his own serve when trailing 5-2, but saved it with a volley to force Thiem to serve for the opener.
Thiem brought up two more set points, only for his forehand to break down with two errors, before a double fault gave Djokovic the chance to break back.
The ninth seed grabbed that opportunity as Thiem miscued again, celebrating exuberantly in front of a delighted crowd as the set went to a tie-break.
And Thiem continued to throw in a series of poor shots, double faulting on Djokovic's first set point as the 30-year-old took the breaker 7-2.
The first few games of the second set went with serve, but Thiem broke for a 3-2 lead on his third break point of the game when Djokovic scooped a wayward backhand off target.
Djokovic, now ranked 13, missed a chance to level immediately and Thiem then continued his momentum to break the faltering Serbian again.
Despite another double fault, Thiem banished the first-set jitters to close out the set at the first time of asking and force a decider.
The key moment came in the seventh game of the third set, when Djokovic lost a 40-15 lead and Thiem broke with a venomous backhand up the line.
And the Austrian closed it out with another break on his second match point.
- Zverev sets up possible siblings clash -
Third seed Alexander Zverev came through a three-set tussle with fellow German Jan-Lennard Struff to set up a potential first ATP Tour meeting with his older brother Mischa.
The 20-year-old, who won two Masters titles last season, became frustrated in the second set but came through 6-4, 4-6, 6-4 and will play either Mischa or Richard Gasquet in the last eight.
Belgian sixth seed David Goffin held off a late fightback from Roberto Bautista Agut to reach the last eight with a 6-4, 7-5 win, in a match that saw the Spaniard accidentally hit a ball boy with the ball.
"I just saw the ball going straight to the ball boy. I was surprised he only had a warning. For me, if you send a ball at the head of a ball boy, you're out," said Goffin.
"I don't know what the rules are exactly and how he could only get a warning. He was saying the ball bounced, and the ball boy just happened to be there. Unlucky for him."
Goffin will play fourth seed Grigor Dimitrov for a place in the semi-finals in a repeat of last year's ATP Tour Finals final, after the Bulgarian came back from a set and a break down to beat Germany's Philipp Kohlschreiber 4-6, 6-3, 6-4.
Second seed Marin Cilic is also into the last eight, after Milos Raonic pulled out with a right knee injury before their third-round match on Thursday.
Croatia's Cilic will face either Kei Nishikori or Italian qualifier Andreas Seppi next.