World number one Serena Williams has reached the semi-finals of the Rogers Cup in Montreal after a hard-fought 4-6 7-5 7-5 victory over Caroline Wozniacki.

Williams, who won her third Canadian trophy last year in Toronto, battled back from a set and a break down to increase her career head-to-head record with the Dane to 7-1.

Wozniacki, who has been ranked as world number one in the past herself, claimed her one and only victory over her American counterpart in Miami in 2012.

Serena will face her sister Venus in the semi-finals after she fought back from a set deficit to beat Carla Suarez Navarro in three sets.