Toronto quarterfinals to be played on Friday

This is the quarterfinal lineup for the Rogers Cup:

Roberta Vinci vs. Samantha Stosur (10)
According to "plan," this quarterfinal was to have been played between Caroline Wozniacki and Stosur, but Vinci ruined the plan. Stosur is doing better at this tournament than she has done in a while, but that doesn't mean she isn't vulnerable to Vinci's tactics.

Agnieszka Radwanska (13) vs. Andrea Petkovic (11)
These two just played each other in the Carlsbad semifinals. In that match, Radwanska showed up with an injured shoulder and Petkovic brought along a gastro-intestinal disorder. Will this match be just as dramatic?

Galina Voskoboeva (Q) vs. Victoria Azarenka (4)
Voskoboeva has taken out Bartoli, Pennetta and Sharapova. Can she do it one more time? These two have not played each other in six years; a lot has changed since 2005.

Lucie Safarova vs. Serena Williams
Safarova has occasionally challenged top players, but she has done so on clay surfaces. The Czech player is in the quarterfinals by virtue of having upset 8th seed Francesca Schiavone. She lost to Williams in the Toronto quarterfinals two years ago, and Williams then lost to eventual champion Elena Dementieva.