Alexander Zverev completed victory over American Jenson Brooksby in the Abierto Mexicano tournament at 4.55 am local time on Tuesday, the latest ever finish for a professional tennis match.
After battling for three hours and 19 minutes, during which the German world number three twice came within a point of losing during a second set tiebreaker, Zverev defeated the 47th-ranked Brooksby 3-6 7-6(10) 6-2.
There were still appreciative tennis fans in the stands at the ATP 500 tournament which has four of the world's top five players participating this year, as the match finished even later than the 2008 Australian Open clash between Lleyton Hewitt and Marcos Baghdatis which ended at 4:34 am.
"Right now I'm happy to have won," defending champion Zverev said on court. "I don't know how Jenson feels. Must be difficult but happy to be a part of history. It was an incredible battle."
It was not the only epic contest on a manic Monday night in Mexico.
American Stefan Kozlov was in the middle of an evening practice session with Rafa Nadal when he found out he was replacing injured Frenchman Maxime Cressy in the main draw as a lucky loser.
"I was playing a practice set with Rafa ... he breaks his string, goes to his bag. I just happen to check my phone for whatever reason," Kozlov said. "I just had an intuition and then I have 20 text messages ... they're like 'get over here'.
"I dropped all my stuff. I told Rafa, he's got a big smile on his face. He's super excited for me ... I got over here and I had about 30 minutes to get ready."
Facing former world number three Grigor Dimitrov, the 130th-ranked Kozlov suffered severe leg cramps after breaking his opponent's serve to take a 5-3 lead in the second set.
Kozlov slumped to the ground in agony and was barely able to move after returning to court as Dimitrov reeled off four successive games to force a decider.
Most people would have expected Kozlov to retire after losing the second set but the 24-year-old displayed incredible mental and physical strength to complete his biggest career win in three hours and 21 minutes.
He will next face either fellow American Denis Kudla or Nadal.
"Today I was totally expecting not to be playing," said Kozlov, adding that he would have retired if he had failed to hold his first service game in the third set against Dimitrov.
"Now I've got the biggest win of my career and I'm about to play Rafa Nadal."
