Novak Djokovic won a rematch of the 2008 Australian Open final against Jo-Wilfried Tsonga to set up a third-round clash with 19-year-old Denis Shapovalov.
Djokovic won in four sets 11 years ago and needed one fewer this time, winning 6-3 7-5 6-4 as the clock ticked towards 1am.
Tsonga has slipped outside the top 100 in the rankings after missing most of last season because of knee surgery, but showed enough here to indicate he will soon be heading in the right direction.
"I've been coming to Australia for the last 15 years... so hopefully I'll be coming for 50 more." We'll still have you when you're 81 @DjokerNole 😉#AusOpen pic.twitter.com/2dPYmg7VVB — #AusOpen (@AustralianOpen) January 17, 2019
Djokovic said afterwards he felt more nervous than usual because of his long history against Tsonga, calling him "one of the greatest rivals that I had throughout my life".
The generational divide was emphasised by Shapovalov describing the possibility of a night match against Djokovic on Saturday as "sick".
The 25th seed insisted he will not be overawed, though, saying of playing the big stars: "Probably two years ago, I was just happy to be on the court with them, get a couple of games. Now I'm thinking how am I going to give a fight to this guy, how am I going to win sets and potentially even the match."
Saturday can not come quick enough for Denis Shapovalov 👊 Can he upset the World No. 1? 🤔#AusOpen pic.twitter.com/1ULx9S8M1P — ATP Tour (@ATP_Tour) January 17, 2019
Shapovalov burst on to the scene two years ago and was immediately hailed as a future star. He is the world's highest-ranked teenager but admitted the expectation has been hard to deal with.
"I felt like I've been doing a lot of soul-searching," he said. "Everything kind of came so quick to me. All of a sudden I was in the spotlight. Now, every week if I lose, 'Denis is disappointing'. It was so much noise.
"Obviously I was blocking most of it out. But still it does get to you. I was just thinking to myself, discussing to my team, 'Is this really what I want? What do I want in life?'
"I came to the realisation, yes, that's what I grew up wanting to do. I want to be a star. I want to be one of the Rogers or Rafas."
Fourth seed Alexander Zverev survived another lengthy battle at a slam, staving off a fightback from Jeremy Chardy to win 7-6 (5) 6-4 5-7 6-7 (6) 6-1.
Stan Wawrinka and Milos Raonic are both working their way back up the rankings after injury problems and contested a high-quality encounter on Rod Laver Arena, which went the way of the Canadian by three tie-breaks to one.
Raonic, who defeated Nick Kyrgios in round one, looks like he could cause significant damage later in the tournament while, for Wawrinka, there was frustration but also encouragement.
Alexander the Great 💪 Zverev survives Jeremy Chardy 7-6(5) 6-4 5-7 6-7(6) 6-1 to reach his third consecutive #AusOpen 3R. pic.twitter.com/MOVsKvVH3f — #AusOpen (@AustralianOpen) January 17, 2019
The 2014 champion said: "It's been a long way to get back. Today I'm sad and frustrated, but, if I take some distance with it, I'm happy to see that I'm able to play again with this level, able to move that well."
Kei Nishikori fought off the challenge from evergreen Ivo Karlovic. The giant Croatian turns 40 next month and his first-round victory over Hubert Hurkacz made him the oldest man to win a main draw singles match here since Ken Rosewall in 1978.
He threatened to back it up with an upset of eighth seed Nishikori, coming back from two sets down to force a deciding set before he eventually lost 6-3 7-6 (6) 5-7 5-7 7-6 (7).
Karlovic said: "I had opportunities against Nishikori who is number nine (in the rankings). In my old age it's unbelievable."
Asked how long he might be able to carry on, he only appeared to be half joking when he said: "If it's like this, another eight or nine years. I don't feel any weakness with my body and my fitness."
It was a landmark day for two Australians, with 19-year-old Alexei Popyrin leading seventh seed Dominic Thiem by two sets to one before the Austrian retired due to illness and Alex Bolt defeating Gilles Simon 2-6 6-4 4-6 7-6 (8) 6-4.
The 26-year-old briefly retired from tennis in 2016 and spent some time as a labourer before returning to the game the following season.
Last year's semi-finalist Chung Hyeon is out, beaten in four sets by Pierre-Hugues Herbert, but there were wins for Borna Coric, Fabio Fognini and David Goffin.
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