US Open organisers said they ejected a fan from Arthur Ashe Stadium early on Tuesday after German 12th seed Alexander Zverev complained the man had used "the most famous Hitler phrase there is" during his fourth-round match.
Zverev, who beat sixth seed Jannik Sinner 6-4, 3-6, 6-2, 4-6, 6-3 in a match lasting almost five hours, was serving in the fourth set when he stopped to draw chair umpire James Keothavong's attention to the spectator.
"He just said the most famous Hitler phrase there is in this world," a furious Zverev told Keothavong. "This is unacceptable. This is unbelievable."
The chair umpire immediately turned around and asked the man to identify himself but he did not come forward. Keothavong then urged fans to remain fair and show respect to both players.
A few minutes later, security personnel stepped onto the side of the court to identify the man with the help of other spectators and eventually ushered him out of the stadium.
"A disparaging remark was directed towards Zverev," a USTA spokesperson said in a statement. "The fan was identified and escorted from the stadium."
Zverev put the incident behind him to seal the victory, which he described as the best moment of his career after his comeback from a serious ankle injury last year.
He meets defending champion Carlos Alcaraz in the quarter-finals.
