Carlos Alcaraz repeatedly slammed his racket on the court in a rare act of frustration as the four-time Grand Slam winner lost 4-6, 7-6 (7-5), 6-4 to Gael Monfils at the Cincinnati Open.

In a match suspended due to rain on Thursday night with players in a second-set tiebreak, the 37-year-old Monfils advanced by taking the final two sets from second-seeded Alcaraz, who described the loss as his “worst game.”

“For me, it was the worst game of my career,” said Alcaraz. “I trained really well. I felt great. But I couldn’t play. I want to forget about it and try to move on to New York.”

When play was suspended, Alcaraz was trailing 1-3 in the tiebreak and hoped to restart when play resumed on Friday, but the No. 3 player in the ATP rankings could not control his emotions.

“This never happened to me before because I could control these feelings,” said Alcaraz. “Today I couldn’t. I felt like I wasn’t playing tennis at all. It was really frustrating for me. At some point I didn’t want to be on the court anymore.”

Alcaraz was playing his first match since winning the silver medal at the Paris Olympics after losing to Novak Djokovic, who also defeated him in the Cincinnati final last year.

Monfils returned to the court later Friday, losing to No. 15 seed Holger Rune 3-6, 6-3, 6-4 as he attempted to become the oldest Cincinnati men’s championship quarterfinalist in the professional era.

“It was a big win for me against Carlos, to be honest, unexpected,” Monfils said. “Playing again in a few hours against (another) good and younger player, I knew it would be tough.”

The US Open begins in New York on August 26th.

Top players who advanced included No. 1 Jannik Sinner, who won by walkover against Jordan Thompson on his 23rd birthday, No. 4 Alex Zverev and No. 6 Andrey Rublev.

Australian Thompson withdrew due to a rib injury.