Top-ranked Serena Williams advanced to the Rogers Cup quarterfinals in Toronto on Thursday night, beating 16th-seeded Andrea Petkovic of Germany, 6-3, 6-2.
The 21-time Grand Slam singles champion will face Italy's Roberta Vinci, a 6-4, 6-3 winner over Russia's Daria Gavrilova.
Williams won titles in Toronto titles in 2001, 2011 and 2013.
Second-seeded Simona Halep of Romania advanced, outlasting 13th-seeded Angelique Kerber of Germany, 6-3, 5-7, 6-4.
Halep will face sixth-seeded Agnieszka Radwanska of Poland, a 6-2, 4-6, 6-4 winner over...