Andy Murray's second-round Wimbledon opponent Stefanos Tsitsipas was booed as he disagreed with the umpire when making a late challenge.
The pair's game ran into the late hours on Thursday and was suspended due to the local council's 11pm curfew on Wimbledon play, meaning they resumed their match on Friday afternoon with Murray holding a two-sets-to-one lead.
After play resumed on Centre Court, Tsitsipas soon hit a return long and then tried to challenge the previous shot. Tsitsipas - who was too late to challenge the call - complained to umpire Aurelie Tourte, who told him firmly that he could not refer to Hawk-Eye.
As he remonstrated and then approached the umpire, he was booed by tennis fans.
Replays showed that the ball was out.
BBC commentator Andrew Cotter said: "You can't play on, miss your next shot and then challenge - and it was way out. Tsitsipas is not at all a happy camper."
Tsitsipas could be heard on TV telling the umpire: "If the ball is out, it's a really bad call from you, and it's going to be out 100%."
