World No.1 Rafael Nadal of Spain progressed to the third round at the Australian Open on Thursday but conceded he could have been more clinical in a straight sets victory over Federico Delbonis of Argentina.

The Spaniard, bidding for a record-equaling 20th Grand Slam title, converted just three of his 20 break point opportunities in a 6-3 7-6(4) 6-1 victory.

"I think I can do lot of things better. But it's not because of Delbonis. I can do things better because of myself. I need to play better," said Nadal.

There were difficult five-set wins for Dominic Thiem of Austria and Karen Khachanov of Russia and former champion Stan Wawrinka of Switzerland, before Australia's home favorite Nick Kyrgios entertained the crowd in a packed Melbourne Arena.

Kyrgios overcame Frenchman Gilles Simon 6-2 6-4 4-6 7-5 in a match where both players mimicked Nadal's service routine after they were handed time violations.

Czech player Karolina Pliskova, Belinda Bencic of Switzerland and Elina Svitolina of Ukraine recorded comfortable wins as all of the top 10 seeded players in the women's draw advanced to the third round in Melbourne for the first time since 2007.

Roger Federer will need to avoid a second Grand Slam upset at the hands of home favorite John Millman if he wants to bring up 100 wins at the Australian Open on Friday.

The 38-year-old Swiss, already the first man to win 100 matches at Wimbledon, can match the feat in Melbourne if he beats Millman, ranked 47, in the third round.

But the 20-time Grand Slam champion is well aware of the challenge posed by Millman, after he was shocked by the Australian in four punishing sets at the 2018 U.S. Open.

"I think the next match is really going to be a test for me because John is going to be there. He's fit like a fiddle," Federer said.

"He's from this country, so naturally also it's going to be different intensity. I think this is going to be a good test for me."

(With inputs from AFP and Reuters)