Samantha Stosur has been dispatched by world No.1 Serena Williams in straight sets at the Toronto Masters.

Three years after falling to Stosur in the US Open final, Williams exacted brutal revenge with a 6-0 6-2 second-round mauling on Wednesday.

French Open champion Maria Sharapova rallied for a three-set victory over Garbine Muguruza.

The fourth-seeded former world No.1 fought back to beat the rising Spanish talent 4-6 6-3 6-1 to set up a meeting with another Spaniard Carla Suarez Navarro, a 6-1 3-6 6-3 winner over Czech Karolina Pliskova in Montreal.

Meanwhile, sixth-seeded German left-hander Angelique Kerber made short work of France’s Caroline Garcia 6-4 6-1 and 11th-seeded former world No.1 Caroline Wozniacki steamrolled Czech Klara Koukalova 6-1 6-2.