French Open and Wimbledon champion Carlos Alcaraz failed to reach the Paris Masters quarter-finals after a thrilling 6-1, 3-6, 7-5 defeat to local favourite Ugo Humbert on Thursday.
The Frenchman, ranked 18th in the world, wrapped up the first set in 26 minutes as Alcaraz struggled to find his rhythm.
Spain's world number two refused to go quietly and took a 5-2 lead before closing out the second set with a hold to love.
But Humbert, buoyed by the home crowd, managed to overpower Alcaraz in the third set and become the first Frenchman to beat a top-five player at the Paris tournament since 2019 when his coach Jeremy Chardy downed Daniil Medvedev in the second round.
"I have to congratulate Ugo. I think his performance has been really high. You know, the way he hits the ball is unbelievable. It's amazing," Alcaraz told a press conference.
The four-times Grand Slam winner added that the speed of the court was a surprise and one of the main factors for his poor performance, saying it had changed a lot from previous years.
"It is the fastest court in the Masters 1000, probably on the tour right now. Probably the fastest one in the last 10 years in this tournament. I play the Davis Cup indoor court, and the court was way slower than this one," Alcaraz said.
Earlier, third seed Alexander Zverev defeated 20th-ranked Frenchman Arthur Fils 6-4, 3-6, 6-3 after recovering from a second-set wobble to set up a clash with Stefanos Tsitsipas.
The 10th-seeded Greek came back from a tight first set to ousted Argentine Francisco Cerundolo 6-7(1), 6-4, 6-2.
Ninth seed Alex de Minaur of Australia also managed to come from behind to beat Britain's Jack Draper 5-7, 6-2, 6-3.
His compatriot Jordan Thompson reached the last eight with a 7-5, 7-6(5) victory over Frenchman Adrian Mannarino. However, Australia's Alexei Popyrin failed to join his countrymen as he fell to Karen Khachanov 7-6(5), 6-4.
Unseeded Russian Khachanov will meet eighth seed Grigor Dimitrov in the quarter-finals after the Bulgarian survived a nail-biting third set tiebreak against Frenchman Arthur Rinderknech to secure a 6-2, 4-6 7-6(5) victory.
Holger Rune struggled against French lucky loser Arthur Cazaux, who had replaced Jannik Sinner after the world number one pulled out with a virus. However, Danish 13th seed Rune recovered from a set down to win 3-6, 6-3, 6-4.
Rune next faces De Minaur while Thompson meets Humbert.