World No. 3 Stefanos Tsitsipas faced audible jeers from the US Open crowds during his second-round win against Adrian Mannarino on Wednesday (1 September).
The Greek won 6-3, 6-4, 6-7 (4-7), 6-0 but was once again criticised for a lengthy mid-match toilet break.
Former champion Andy Murray raised the issue during the previous round but fans were once again made to wait over eight minutes for the player.
Upon his return, Tsitsipas was met by a chorus of boos from the crowd at Flushing Meadows.