World number one Ashleigh Barty and US Open champion Naomi Osaka both recorded strong wins to start their seasons in Australia.

Barty was playing her first official match for nearly a year having chosen to stay at home in Australia when the tour resumed last summer following the coronavirus-related shutdown.

The 24-year-old is the top seed in the Yarra Valley Classic and she was a convincing 6-3 6-3 winner against Ana Bogdan in front of a surprisingly sparse crowd at Melbourne Park.

Barty said: "I think overall I felt pretty good. Ana did an exceptional job in making me play to a very high standard. I knew right from the first point I was going to have to be ready tonight and switched on straight away. That was really nice to have that challenge."

Petra Kvitova won a high-quality contest to end the day, beating 40-year-old Venus Williams 7-6 (6) 7-5, while sixth seed Garbine Muguruza thumped Alison Van Uytvanck 6-2 6-0.

Australian Open champion Sofia Kenin had just won the first set 7-5 against Camila Giorgi when the Italian retired.

Osaka was playing her first match since lifting her third slam title in New York last September and eased past Alize Cornet 6-2 6-2 at the Gippsland Trophy.

The Japanese second seed said: "I was definitely really nervous going into it. But I'm really happy with how positive I was throughout the match."

In the third round Osaka will face Britain's Katie Boulter, who upset Coco Gauff 3-6 7-5 6-2.

French Open champion Iga Swiatek was playing her first match as a grand slam winner and made a nervous start against Kaja Juvan but recovered to win 2-6 6-2 6-1.

Fifth seed Johanna Konta eased to a 6-2 6-3 win over Bernarda Pera but fourth seed Aryna Sabalenka, who was on a 15-match winning streak, was surprisingly beaten 6-1 2-6 6-1 by Kaia Kanepi.