Jack Draper was penalised with a controversial hindrance call as Daniil Medvedev ended the Briton's Indian Wells title defence in the quarter-finals.
Draper fell to a 6-1 7-5 defeat by former world number one Medvedev, but the Russian was booed after the tense moment midway through the second set.
World number 14 Draper, serving at 5-5 0-15, briefly stretched his arms out wide during a rally to signal he thought Medvedev's forehand had gone long.
The rally continued for another seven shots before Medvedev netted a backhand.
Two-time finalist Medvedev then asked umpire Aurelie Tourte for a video review to see whether Draper had been guilty of hindrance - making either an action or a noise to disturb an opponent.