What to expect at Australian Open on Day 5

American teenager Coco Gauff has promised to be more aggressive against holder Naomi Osaka in the third round of the Australian Open, on Friday, as she hopes for a different outcome in their second career meeting.

A nervous Gauff was beaten 6-3, 6-0 by Japan's Osaka in the third round of the US Open last year but the 15-year-old said after her three-set victory over Romania's Sorana Cirstea on Wednesday that things would be different.

"I'll be less nervous this time ... (at the) US Open I was nervous. It was my first time on Arthur Ashe," Gauff, who downed seven-time Grand Slam winner Venus Williams in her tournament opener in Melbourne, told a news conference.

"We're both familiar with each other's games. She plays really aggressive. This time coming in I'm going to be more aggressive ... I think I'm more confident this time around."

World number one Ash Barty will look to continue her strong start to the tournament but the home hope could face a tricky third-round test against Hobart International champion Elena Rybakina in their first meeting.

Roger Federer will play Australian battler John Millman, who beat him at the 2018 US Open, while Novak Djokovic takes on Japan's Yoshihito Nishioka for a place in the fourth round.

In other matches, 23-time Grand Slam singles champion Serena Williams plays China's Wang Qiang, Petra Kvitova meets Ekaterina Alexandrova and Caroline Wozniacki faces Ons Jabeur.

Among the men, sixth seed Stefanos Tsitsipas faces the big-serving Milos Raonic while Marin Cilic meets Roberto Bautista Agut and Guido Pella plays Fabio Fognini.