The pair advanced on a day of serene progress for the top names of tennis, with Australian world number one Ashleigh Barty, American superstar Serena Williams and Swiss legend Roger Federer all going through with ease.

Serbia's second seed Djokovic has won the Australian Open a record seven times and is hoping to capture his 17th Grand Slam.

He powered past Japanese wildcard Tatsuma Ito, 6-1, 6-4, 6-2.

"My serve was working extremely well in the first round and second round," Djokovic said.

"That's something I worked on in the off-season. 

"That's one of the priorities I guess of the training sessions, trying to get that advantage of winning a lot of easy points on the first serve."

Federer, the third seed, breezed past Serbia's Filip Krajinović 6-1, 6-4, 6-1.

He is hoping for a 21st grand slam crown and a seventh in Australia.

Greek sixth seed Stefanos Tsitsipas, the World Tour Finals champion, advanced without playing, after Germany's Philipp Kohlschreiber pulled out with a muscle injury.

Australia's John Millman provided home cheer with a 6-4, 7-5, 6-3 win over Poland's 31st seed Hubert Hurkacz, but Italy's eighth seed Matteo Berrettini was the big casualty of the day.

He went down 7-6, 6-4, 4-6, 2-6, 7-5 to American Tennys Sandgren.

In the women's draw, Japan's third seed Osaka brushed aside China's Zheng Saisai 6-2, 6-4 as she continued her bid for a third grand slam.

Top seed Barty was too strong for Slovenia's Polona Hercog, 6-1, 6-4.

The Australian is hoping to become the first home winner of a singles title in Melbourne since Chris O'Neil captured the women's crown in 1978.

"It was a clean match, [I'm] really happy to get out of that one," Barty, last year's French Open champion, said

"It was very different end to end, the wind played a massive factor.

"Polona has the ability to hit you off the court, so it was about me making as many balls as I could and I was able to save a few break points in the second set as well." 

Eighth seed Williams needs just one more grand slam to draw level with Australian Margaret Court's all-time record for men and women on 24.

She has won seven times in Australia and today beat Tamara Zidanšek of Slovenia 6-2, 6-3.

American 15-year-old Coco Gauff continued her emergence with a 4-6, 6-3, 7-5 win over Romania's Sorana Cîrstea and will now play Osaka.

Denmark's 2018 Australian Open champion Caroline Wozniacki beat Ukraine's 23rd seed Dayana Yastremska 7-5, 7-5, and the Czech Republic's two-time Wimbledon champion Petra Kvitová, the seventh seed, won by the same score against Spain's Paula Badosa. 

The biggest seed to exit was 11th-ranked Aryna Sabalenka of Belarus, beaten 7-6, 7-6 by Spain's Carla Suárez Navarro.