Britain's Jacob Fearnley says he was caught "off-guard" by a noisy US Open crowd as German third seed Alexander Zverev made his greater experience count in a second-round win.
Fearnley, 24, showed spirit to save five match points against the three-time major finalist, but it was too late to stop his New York main-draw debut coming to an end with a 6-4 6-4 6-4 defeat.
The pair played in Thursday's night session on Louis Armstrong Stadium, which is infamous for a constant hubbub of chatter during matches.
"I hadn't played on a court with that much noise before – it caught me by surprise," said 60th-ranked Fearnley, who only made his professional debut last year.