World number one Novak Djokovic faces French journeyman Adrian Mannarino for a place in the Australian Open quarter-finals on Sunday, as Aryna Sabalenka resumes her title defence against Amanda Anisimova.
Top seed Djokovic recaptured his top form to surge into the last 16 after dropping sets in his opening two matches, and warned he will only get better as he chases an 11th title.
"Coming into the tournament I haven't really felt great health-wise, physically, and also game-wise. It's all connected obviously," said the Serb, who is gunning for a record 25th Grand Slam crown.
"But I'm in the fourth round. I believe that things will progress as the tournament goes on."
That will be a worry for Mannarino, who at 35, is a year younger than his Serbian opponent and enjoying a late career resurgence.
The pair have met four times before, but not since 2018, with Djokovic winning each time.
Djokovic almost always plays the night session on Rod Laver Arena, but has been bumped to the afternoon this time.
That's because home hope Alex de Minaur, seeded 10, is bidding to make the last eight for the first time, with Russian fifth seed Andrey Rublev standing in his way.
In other fourth-round action, in-form fourth seed Jannik Sinner faces last year's semi-finalist Karen Khachanov on Margaret Court Arena.
The man who beat him in that semi-final, Stefanos Tsitsipas, who is the seventh seed, takes on 12th-seeded American Taylor Fritz.
There are just three top-10 seeds left in the women's draw and they are all in action on Sunday.
World number two Sabalenka has been in ominous form in Melbourne, dropping just six games in her three matches.
That included a 6-0, 6-0 demolition of Lesia Tsurenko in the third round, with Anisimova next in her sights.
"We had a lot of great matches against each other, always tough battles," she said of the American, who is on the comeback trail after an eight-month break for burnout.
"I'm not expecting, like, easy matches, because when you're getting to the last stages of the tournaments, it's not going to be easy at all."
US Open champion and fourth seed Coco Gauff has also been in good touch and is up against Poland's Magdalena Frech as she attempts to reach the quarter-finals for the first time.
Russia's unseeded 16-year-old Mirra Andreeva fronts up against ninth seed Barbora Krejcikova to keep her dream run going, while Ukraine's Marta Kostyuk takes on Russian qualifier Maria Timofeeva.
