MELBOURNE: World number one Ash Barty marked her return to competitive tennis after almost a year out with a 6-3 6-3 win over Romania's Ana Bogdan in the second round of Yarra Valley Classic on Tuesday.

The 24-year-old Australian had not played a competitive match since last February due to the COVID-19 pandemic, opting to skip the US Open and not defend her title at the rescheduled French Open in September.

Barty went down narrowly to world number two Simona Halep in last week's exhibition event in Adelaide but was back to winning ways on Tuesday, facing a single breakpoint on her serve in the match.

"I had so much fun out here today, and I think I missed you guys so much as well," Barty, who had a bye in the opening round, told the handful of fans present at Melbourne Park's Margaret Court Arena.

"This is one of my favourite places to play in the entire world, and for me to be able to come back after 11 or 12 months off now- it's been a while, but I miss this feeling, I miss coming out here and competing."

Top seed Barty hit her sixth ace of the match to convert her fourth match point and will next meet Czech Marie Bouzkova.

Australian Open champion Sofia Kenin had won the opening set 7-5 when Italian Camila Giorgi retired from their second-round clash with a left thigh injury.

"This obviously is not the way I wanted to win. I hope she's going to feel better for the Aussie Open," American Kenin, who will next face compatriot Jessica Pegula, told reporters.

"It's unfortunate, but I feel like I played well. It's a win. I'm going to take it, of course."

Other Grand Slam champions also advanced at the WTA 500 event on Tuesday with two-time Wimbledon champion Petra Kvitova and Garbine Muguruza, who won the French Open in 2016 and Wimbledon the following year, picking up contrasting wins.

Kvitova found a way past seven-times major winner Venus Williams with a 7-6(6) 7-5 win while last year's Australian Open finalist Muguruza strolled past Alison Van Uytvanck 6-2 6-0.