SYDNEY - Germany's Angelique Kerber overcame the loss of the first set on a day of extreme heat in Sydney as she maintained her build-up to next week's Australian Open on Monday.

The fourth seed, one of the few members of the women's world top 10 not to be hit by injury in the lead-up to the year's first Grand Slam, came from a set down to oust Ukraine's Elina Svitolina 4-6, 6-0, 6-3 in Sydney International's first round. Kerber, who lost to Victoria Azarenka in Saturday's Brisbane International final, is looking for more matches to hone her form leading into the Australian Open in Melbourne.

While defending champion Petra Kvitova and second seed Agnieszka Radwanska pulled out of the Sydney event citing injuries, Kerber powered on to get in some valuable match practice. Kvitova and Radwanska's withdrawals came after injury problems at other Australian tournaments for the world's top-ranked stars including Serena Williams (knee), Simona Halep (Achilles), Garbine Muguruza (foot) and Maria Sharapova (forearm).

"I had a lot of matches last week, but that was actually also my plan to come to Australia, to have a lot of matches, and also to play a few more matches here," Kerber said. "I don't know how far I can get. I'm healthy. I have no pain anywhere. I will just try to recover and see how I feel tomorrow. But my body feels good."

Kerber struggled with the intense heat early in her match, dropping the opening set without winning a game, but she battled on. "It's good to have a match like this under my belt. It's always hot in Australia. I think it was a good match to prepare for Melbourne," she said.

With temperatures hitting 37 Celsius (99 Farenheit) the WTA's extreme heat policy came into force, allowing Kerber and Svitolina to take a 10-minute break before the third and deciding set. Australia's Samantha Stosur fought back from a set and a service break down to overcome defeat Italy's Roberta Vinci 4-6, 7-5, 7-5 in two hours 30 minutes.

Among other first-round winners on Monday were Italy's world number 19 Sara Errani, over Spanish seventh seed Carla Suarez 6-3, 6-3, and German Sabine Lisicki, who eased past Slovenia's Polona Hercog 6-4, 6-3. In the men's draw, Italian fifth seed Andreas Seppi eliminated Denis Istomin of Uzbekistan in three sets, but Seppi's compatriot Simone Bolelli went out to American qualifier Alexander Sarkissian 6-2, 7-6 (7/5). In the evening match, experienced Spaniard Tommy Robredo was too strong for Australia's John Millman 7-6 (7/3), 6-3.