MELBOURNE, Australia — Serena Williams has beaten China's Peng Shuai in straight sets to advance to the fourth round of the Australian Open.

Williams, who won the singles titles at Melbourne Park in 2003, 2005 and 2007, beat Peng 6-1, 6-4 to start off Saturday's play at Rod Laver Arena.

Peng was up a service break in the second set before Williams leveled in the sixth game, then held to take a 4-3 lead that she never relinquished.

The nine-time Grand Slam singles champion next will play either former champion Amelie Mauresmo of France or Victoria Azarenka of Belarus, whose match followed on center court.