Melbourne - Rafael Nadal faces a player he calls "one of the best in the world" at the Australian Open on Friday as Caroline Wozniacki has a showpiece clash against fellow champion Maria Sharapova.
The Spaniard said he had plenty of respect for Australian 27th seeded teenager Alex de Minaur, who won the Sydney International last week and is on seven-match win streak.
"I think he improved a lot during the last three years. Today (he) is one of the best players of the world. That's the real thing," said 17-time Grand Slam champion Nadal, seeded two.
"He's young, very young. He is winning a lot of matches. So let's see. Going to be a tough one."
They are the feature men's night match on Rod Laver Arena, followed by women's second seed Angelique Kerber in action against Kimberly Birrell.
The German Wimbledon champion, who lifted the Melbourne trophy in 2016, has had two comfortable wins so far and should have little trouble against the 240th ranked Australian.
Six-time Australian Open champion Federer has also looked in good nick and has American Taylor Fritz up next, who is 16 years his junior but has risen to 50 in the world.
The Swiss great, the defending champion, is in the third round at Melbourne Park for an incredible 20th straight year and is angling for a 21st major title.
In a mouth-watering clash, fellow defending champion Wozniacki takes on Sharapova, who has been in sizzling form, dropping only three games in the first two rounds.
The five-time Grand Slam winning Russian, who is battling back to form after a 15-month drugs ban, conceded she was the underdog.
"Relatively speaking on paper, if you're looking at numbers, yeah, absolutely," she said. "She's number three in the world. I mean, I think that speaks for itself in terms of her game, her confidence, everything else."
Wozniacki's one and only Slam title was in Melbourne last year and she is now dealing with rheumatoid arthritis that has threatened to derail her career.
The Dane is just happy to be back at the scene of her greatest triumph.
"It feels amazing. I felt at home straight away when I got here," she said.
In other matches, last year's losing finalist Marin Cilic, seeded six, plays Spain's Fernando Verdasco while Greek 14th seed Stefanos Tsitsipas takes on Russia's Nikoloz Basilashvili.
Among the women, former US Open winner Sloane Stephens is in action, as is eighth seed Petra Kvitova.