Vinci, a three-time champion on the WTA circuit this season, ousted the Danish Wozniacki in 6-4, 7-5 fashion in 1 hour, 52 minutes Wednesday on the hardcourts at Rexall Centre.
Wozniacki beat U.S. Open runner-up Vera Zvonareva in last year's Rogers Cup finale in Montreal, as this event shifts between Toronto and Montreal each year.
French Open champion and Australian Open runner-up Li Na, seeded sixth this week, advanced via walkover, as fellow Chinese Peng Shuai was unable to go due to a hip injury, while seventh-seeded Wimbledon titlist Petra Kvitova of the Czech Republic handled Spaniard Anabel Medina Garrigues 7-6 (7-3), 6-3 and eighth-seeded French Open runner-up Francesca Schiavone of Italy leveled Russian Ekaterina Makarova 6-1, 6-3.
Last week's Carlsbad champion Agnieszka Radwanska, seeded 13th this week, continued her winning ways with a 6-3, 6-3 victory over Croatian qualifier Petra Martic on Wednesday.
The 2011 Rogers Cup champion will earn $360,000.