Third seed Daniil Medvedev survived a scare at the Australian Open as he came from two sets down to beat Emil Ruusuvuori in a match that finished at 3.40am.
Medvedev looked like he might have been in bed much earlier as the unseeded Finnish player took control.
But the Russian showed his fighting spirit to ensure that it turned into an early morning as he battled back to win 3-6 6-7 (1-7) 6-4 7-6 (7-1) 6-0, with sunrise two hours away.
Carlos Alcaraz came through a tough four-set battle with Italy's Lorenzo Sonego on a day of close encounters for the big names in Melbourne.
Novak Djokovic’s struggles will have given heart to his rivals but few are finding the early stages of the tournament straightforward, and second seed Alcaraz needed three hours and 25 minutes to defeat Sonego 6-4 6-7 (3-7) 6-3 7-6 (7-3).
In a match full of shot-making, Alcaraz topped the highlight reel with two winners around the net post.
"I didn’t feel I had downs in the match," said the Spaniard. "In the tie-break, he started to play an unbelievable game. I think he made some big returns after a good first serve from me.
"I think probably I could do something else in the tie-break. But the level that he played, it was really, really high."
Sixth seed Alexander Zverev survived an almighty scare as the former semi-finalist dug deep to beat Slovakian qualifier Lukas Klein 7-5 3-6 4-6 7-6 (7-5) 7-6 (9-7) and move into the third round.
Rain forced the contest to be completed under the roof on John Cain Arena and Zverev found himself in huge trouble as world number 163 Klein turned up the pressure after losing the opening set to take the next two.
"I would have much rather won in an hour-and-a-half but what can I do," Zverev said. "He played incredible, was hitting every ball as hard as he could from both sides. I didn't really know what to do a lot of the times.
"To be honest, he probably deserved to win more than me. That's how tennis goes sometimes. I'm happy that I'm through but his ranking is no value to how he's playing."
The 25-year-old Klein, whose only previous grand slam main draw appearance was at Wimbledon in 2022, was inching towards his first career top-10 win but squandered the chance to break at 4-4 in the fourth set, much to Zverev's relief.
"I was thinking there's a Qantas flight at 11pm tonight straight to Dubai and then one to home," Zverev said, adding that he was just a spectator much of the time as Klein reeled off the winners, finishing with 80 in total.
"I was playing but the match was his hands, he was playing winners or he was missing ... I'm extremely happy to be honest."
But Klein also made 83 unforced errors, compared to only 36 from Zverev, and that proved to be the difference.
Zverev levelled the contest as Klein frittered away a 3-1 lead in the tie-break and the 26-year-old German swapped breaks with his opponent early in the decider before holding his nerve in a tie-break to prevail.
"Now I'm in the third round," said Zverev, who will next face American Alex Michelsen. "It's about recovering and being out here on court because that's what I love to do."
Casper Ruud, the men's 11th seed, was also forced to battle hard for his place in the third round as he was taken to a fifth set tie-break by local Max Purcell before winning 6-3 6-7 (7-5) 6-3 3-6 7-6 (9-7).
Ruud thought his match against the unorthodox Purcell was one he might have lost before the boost of confidence he got from a fine showing at the year-opening United Cup.
"That's a typical match you could end up losing," he told reporters.
"Today I didn't have to save match point, but he was basically only three points away from winning. It might be the good start I had in United Cup that gave me some confidence to stay in the rally and play well when I had to."
The Dane will next face British 19th seed Cameron Norrie, who also needed the full five sets to beat Italian qualifier Giulio Zeppieri 3-6 6-7 (4-7) 6-2 6-4 6-4.
