AP, Toronto :Top-ranked Serena Williams advanced to the Rogers Cup quarterfinals Thursday night, beating 16th-seeded Andrea Petkovic of Germany 6-3, 6-2.”I think I served better,” Williams said. “It was a big difference. I still think I have a tremendous amount of improvement to do off the ground and everywhere else.”Williams won titles in Toronto titles in 2001, 2011 and 2013. The 21-time Grand Slam singles champion will face Italy’s Roberta Vinci, a 6-4, 6-3 winner over Russia’s Daria Gavrilova.Second-seeded Simona Halep of Romania also advanced, outlasting 13th-seeded Angelique Kerber of Germany 6-3, 5-7, 6-4 in hot afternoon conditions.”I did well in the last game,” Halep said. “I said, ‘I have to win it because I cannot move anymore.'”Halep will face sixth-seeded Agnieszka Radwanska of Poland, a 6-2, 4-6, 6-4 winner over Alize Cornet of France.
