Toronto: American Serena Williams reached the semi-finals as she rallied from a first set loss to defeat Lucie Safarova 4-6, 6-3, 6-4 at the $2.05 million WTA hardcourt tournament on Friday.
The unseeded Williams, who is continuing her comeback from injury and illness, next faces fourth-seeded Victoria Azarenka of Belarus, who breezed past world number 135 Galina Voskoboeva of Kazakhstan with a 6-1, 6-2 win.
Australia's Samantha Stosur also advanced to the next round easily beating Roberta Vinci - the conqueror of world number one Caroline Wozniacki - 6-4, 6-1.
Stosur broke Italian Vinci's serve while leading 5-4 in the first set to take the opening set at the Rexall Centre facility.
The Aussie then stepped up her game in the second set and moved through to the semi-finals with authority.
"As the match went on, I obviously probably grew in confidence, and then you get that bit of a lead with a buffer of a couple breaks and felt like I could maybe start going for a bit more," Stosur said. "I went for some big ones and it paid off."
Stosur next faces Poland's Agnieszka Radwanska, who beat German Andrea Petkovic 6-4, 6-3.
"Semi-finals, you've got to believe that anything in possible," Stosur said.
"Having said that, from semi-finals to winning the tournament, there's a still a long way to go, but I think in this position you've got to. If you don't, then it's probably a little bit silly."
Azarenka is the highest seeded player left in the field. Voskoboeva leaves with her head high as she earned the title giant killer at this tournament after upsetting No. 9 Marion Bartoli, No. 25 Flavia Pennetta and former US Open winner Maria Sharapova to earn her spot in the quarter-finals.