MELBOURNE, Australia (AP) -- Sixth-seeded Agnieszka Radwanska moved into the fourth round of the Australian Open on Saturday with a 6-0, 7-5 win over Uzbekistan-born American Varvara Lepchenko.

Opening the day's play on Rod Laver Arena, Radwanska won the first set in 25 minutes before Lepchenko took a medical timeout, appearing to be affected by the heat.

Radwanska, with her new coach Martina Navratilova watching from the stands, was broken while serving for the match but broke Lepchenko's serve to clinch it three games later.

Radwanska, a semifinalist here last year and a finalist at Wimbledon in 2012, will play either Camila Giorgi of Italy or No. 18-seeded Venus Williams in the next round.