Serena Williams lost just two games Saturday in sailing through a third-round victory at the Australian Open. Williams, the No. 12 seed, won 72 percent of the points on serve and nearly 60 receiving in a 6-1, 6-1 win over Greta Arn. Williams fought off all four break points she faced in her third consecutive straight-set win at the Australian Open in Melbourne. Second-seeded Petra Kvitova had piled up 20 winners and built a 6-0, 1-0 lead when No. 27-seeded Maria Kirilenko retired with a leg injury. Kvitova lost just two points on serve in the abbreviated match. Maria Sharapova continued her sharp run with a 6-1, 6-2 win over 30th-seeded Angelique Kerber. Sharapova, seeded fourth, has lost just five games over her three matches this week. She took 59 percent of the points off Kerber\'s serve and finished off six of her nine break-point chances. Ekaterina Makarova pulled off the upset of the day, knocking off seventh-seeded Vera Zvonareva 7-6 (9-7), 6-1 but Zheng Jie also advanced with an upset, beating No. 9-seeded Marion Bartoli 6-3, 6-3. Also in Saturday\'s third-round play, No. 14 Sabine Lisicki topped 18th-seeded Svetlana Kuznetsova 2-6, 6-4, 6-2; 21st-seeded Ana Ivanovic defeated Vania King 6-3, 6-4 and Sara Errani was a 6-7 (6-8), 6-0, 6-2 winner over Sorana Cirstea. Kvitova draws Ivanovic in the fourth round while Errani and Zheng meet in the other match in that quarter of the draw. Sharapova could meet Williams in the quarterfinals if Sharapova gets past Lisicki and Williams beats Makarova in the fourth round.