Australians Samantha Stosur and Casey Dellacqua have scored wins in the opening round of the Toronto Masters in Montreal.

Australians Samantha Stosur and Casey Dellacqua have made winning starts to their Toronto Masters campaigns in Montreal, but both face an uphill battle in the second round.

Stosur dispatched Puerto Rico’s Monica Puig 6-2 6-2 to set up a clash with world No.1 Serena Williams in a rematch of the 2011 US Open final, which the Queenslander won.

Tuesday’s victory was Stosur’s second over Puig in recent months and snapped a four-match losing streak for the former world No.4.

Her last win was almost two months ago, in the first round of the WTA grass tournament in Birmingham.

Williams enters the second round off a bye, after claiming the Stanford Classic title in California on Saturday.

Dellacqua took just under 90 minutes to beat Belgium’s Kirsten Flipkens 6-0 4-6 6-2.

It was the world No.31’s third victory over Flipkens this year, following wins at the Australian Open and at Indian Wells.

Dellacqua will next play second seed and reigning Wimbledon champion Petra Kvitova.

Polish third seed Agnieszka Radwanska became the first player to reach the third round of the tournament after beating Barbora Zahlavova Strycova 6-4 6-4.

Venus Williams also advanced on Tuesday, but the world No.26 needed three sets to beat Russian Anastasia Pavlyuchenkova 6-1 3-6 6-2.

“It felt good to get through this match and kind of hopefully gain that momentum for the rest of the week,” said Williams, who next faces qualifier Yulia Putintseva.

In other opening-round action that involved former world No.1s, ninth-seeded Serb Ana Ivanovic drubbed Swiss qualifier Timea Bacsinszky 6-1 6-2 and 11th-seeded Caroline Wozniacki slammed Slovak Daniela Hantuchova 6-1 6-1.

Spaniard Carla Suarez also rolled over Serb Bojana Jovanovski, while American qualifier Coco Vandeweghe cruised past China’s Zhang Shuai.