Britain's former world number one Andy Murray says he may not play his Washington Open quarter-final after sealing his third-round victory at 03:02 local time.
Murray, 31, broke down in tears after beating Romanian Marius Copil 6-7 (5-7) 6-3 7-6 (7-4).
The Scot is due to play Alex de Minaur of Australia in the quarter-finals later on Friday.
"I don't know how players are expected to recover from that," Murray said.
"Not playing, potentially, is possible.
"My body doesn't feel great right now. Finishing matches at three in the morning isn't good for anyone involved in the event - players, TV, fans, anyone.
"When you're expected to come back and perform the next day, I think that's unreasonable."
Three-time Grand Slam champion Murray is playing only his third tournament since hip surgery in January and his last eight tie with de Minaur would mark his first quarter-final since Wimbledon in 2017.
Murray - now ranked 832 in the world - lost the first set against Copil in one hour and six minutes, having taken a 5-0 lead in the tie-break before losing seven points in a row.
He broke Copil twice in the second set to take it in 45 minutes and looked set to take the third comfortably when he secured a break in the sixth game to move 4-2 up.
But the Romanian, ranked 93rd, immediately broke back before holding serve to level the match, before Murray's fitness prevailed in the deciding tie-break.
An emotional Murray then sat courtside and sobbed into his towel.
The tournament's previous latest finish was 02:27 local time.