Reigning Australian Open champion Naomi Osaka won as expected in a windy Melbourne - and may now face off against 15-year-old grandson Coco Gauff in the third round.

Osaka, ranked third in the world, defeated 42-ranked Chinese Saisai Zheng in straight sets, 6-2, 6-4.

But victory did not come without hardships. Zheng took the lead directly in the second set and pulled away by 4-2, before Osaka got together and won the next four games. The 22-year-old Japanese showed a hot temper on the track as she threw her racket into the floor and gave it a kick.

- I just wanted to be fooled, I've been in this situation before and I felt that I really didn't want to play a third set this time, says Osaka.

Home jumping on

The next obstacle for the title defender and the former world set may be American super talent Coco Gauff, who knocked out Venus Williams in the first round. Gauff meets Romanian Sorana Cirstea in her second round later today.

World set and homecoming Ashleigh Barty didn't have to tear herself away. In 66 minutes she had disarmed Polona Hercog, the winner of the French Open. 6-1, 6-4 became the final figures at Rod Laver Arena.

- It was very difficult in the end. I think the wind was an important factor especially with the new ball, says the Australian, who many in the audience hope to be the first home winner in the tournament since 1978.

Wozniacki moved

Caroline Wozniacki is not ready to put the tennis racket on the shelf just yet. The Danish defeated Ukraine's Dayana Yastremska by 7-5, 7-5. With fine defensive play, she compensated for a certain lack of power in the battles, forcing the aggressive Ukrainian to make mistakes.

- It got a little emotional for me. The audience really stood behind me and it was so special, said a teary-eyed Wozniacki.

In the next round she will meet Tunisian Ons Jabeur.