Second seed Stefanos Tsitsipas was dumped out of the Paris Masters on Tuesday after losing to in-form Frenchman Ugo Humbert in a marathon second-round tie.
Humbert, who is on a seven-match winning streak after winning the Antwerp title last month, missed four match points but battled to a 7-6(4), 6-7(6), 7-6(3) victory.
He was visibly struggling in the final-set tie-break after over three hours on court, but Tsitsipas said he was also not at full fitness.
“I'm just disappointed with the way I played,” said the World No. 6, who lost to World No. 1 Novak Djokovic in an epic French Open semifinal last month.
“During the second set, my Roland Garros injury came back, and it wasn't as bad as at the French Open, but it kind of had me on the edge of things, and I wasn't sure if that's good for me to be out there.
“But that's not an excuse, for sure. I still fought and gave my best out there, despite this thing that I had on court.”
The 22-year-old Humbert will face former US Open champion Marin Cilic for a place in the quarterfinals.
Tsitsipas will next defend his ATP Tour Finals title in London at the season-ending tournament which gets underway on November 15.
The results: Second round: 9-Pablo Carreno Busta bt Jan-Lennard Struff 7-6(3), 6-2; Norbert Gombos bt 8-David Goffin 6-4, 7-6(6); Marcos Giron bt 7-Matteo Berrettini 7-6(3), 6-7(0), 7-5; Marin Cilic w/o Corentin Moutet; Ugo Humbert bt 2-Stefanos Tsitsipas 7-6(4), 6-7(6), 7-6(3).
First round: Miomir Kecmanovic bt John Millman 6-4, 6-2; Yoshihito Nishioka bt Pablo Andujar 5-7, 6-4, 6-2; Adrian Mannarino bt Dusan Lajovic 7-6(5), 6-3; 12-Stan Wawrinka bt Dan Evans 6-3, 7-6(3); Tommy Paul bt Gilles Simon 3-6, 6-3, 6-3; Richard Gasquet bt Taylor Fritz 6-0, 3-6, 6-3; Lorenzo Sonego bt Alexander Bublik 6-1, 6-4; Kevin Anderson bt Laslo Djere 5-2 (retired); Pierre-Hugues Herbert bt Tennys Sandgren 2-6, 6-4, 7-6(4); 10-Milos Raonic bt Aljaz Bedene 6-3, 6-2 .