Stefanos Tsitsipas accused a U.S. Open chair umpire of having a bias against him during a tirade in which he told the official, "You're all weirdos!"

Tsitsipas told Damien Dumusois that the cause of his bias was "because you're French probably and you're all weirdos!"

The argument came midway through the fourth set of Tsitsipas' 6-4, 6-7 (5), 7-6 (7), 7-5 loss to Andrey Rublev on Tuesday, a day when he and fellow young star Dominic Thiem both lost in the first round for the second straight major tournament.

Tsitsipas, the No. 8 seed from Greece, appeared to be battling cramps and was slow to return to the court after losing his serve.

Dumusois told Tsitsipas it was time to play, but Tsitsipas was still reaching into his bag for a new headband and screamed at Dumusois that he still needed time to change. Dumusois responded that Tsitsipas would be penalized.

"I don't care," Tsitsipas replied. "Do whatever you want, because you're the worst."

"I don't know what you have against me," Tsitsipas continued. "Because you're French probably and you're all weirdos! You're all weirdos!"

Dumusois is indeed French.

Tsitsipas had been angry that Dumusois believed he was getting coaching during the match from his father, Apostolos, which is not allowed.

"The chair umpire was very incorrect in what he was telling me during the match," Tsitsipas said afterward. "I don't know what this chair umpire has in specific against my team, but he's been complaining and telling me that my team talks all of the time when I'm out on the court playing. He's very — I don't know. I believe he's not right, because I never hear anything of what my team says from the outside."

Tsitsipas added that he thought tennis needed more umpires who are fair to all players.

"I feel like some of them have preferences when they are on the court," he said.

Tsitsipas opened his Grand Slam season by beating Roger Federer en route to the Australian Open semifinals. He fell at Wimbledon to Thomas Fabbiano, who then sent Thiem to another quick exit by beating the No. 4 seed 6-4, 3-6, 6-3, 6-2 on a day when four top-10 seeds in the bottom half of the bracket were upset.

The two-time French Open runner-up said he was battling an illness leading into the tournament and said he was exhausted after two sets.

"I'm far away from 100%," Thiem said. "Like this, it's very tough to win."

Tsitsipas was clear that his problems stemmed from the influence of Dumusois.

"Well, it's not very pleasant when you have the umpire give you warnings and time violations and coaching violations during a match," Tsitsipas said. "It can affect your thinking. It can affect your decision-making."