World number two Carlos Alcaraz was knocked out of the Paris Masters by 18th-ranked Ugo Humbert of France who swept to a third round victory in three sets on Thursday.

Left-handed Humbert came through 6-1, 3-6, 7-5 to register his first win over the French Open and Wimbledon champion having lost twice to the Spanish star earlier in 2024.

It was a testing evening for Alcaraz who was 0-5 down in the first set before he managed to get on the board.

"I'm just super proud of myself that I did it," said Humbert who has won titles in Marseille and Dubai this season. "It was a crazy match, a crazy atmosphere."

"I went for every shot," added Humbert, looking back on his first set blitz.

"That's why I think I had less energy in the second set, and after the third it was a mountain that was with me to the end," he said. "I trusted myself in big moments and I made some big shots."

The 21-year-old Alcaraz has endured a rollercoaster second half of the season since his heartbreaking Paris Olympics final loss to Novak Djokovic.

"It was a very intense match," admitted Alcaraz. "I started with some doubts about my game. Against a player who attacks whenever he can, who hits very aggressively at the slightest opportunity, it wasn't easy to get into the match."

"I was not up to the level he displayed," he added. "Ugo's performance was really high – the way he hits the ball is incredible."

Alcraz was knocked out in the second round of the US Open by 74th-ranked Botic van de Zandschulp, and defeated top-ranked Jannik Sinner in the Beijing final.

He then suffered a quarter-final exit at the hands of Tomas Machac, the world number 33, at the Shanghai Masters.

Humbert goes on to face Australia's Jordan Thompson for a place in the Paris Masters semi-finals.

The French number one just edged Alcaraz in winners on Thursday with 28 to 23 with both men committing 38 unforced errors. (AFP)