Playing with a tape on her right ankle, former world No. 1 Caroline Wozniacki slumped to a 6-2, 6-2 defeat to Petra Cetkovska in the second round of Wimbledon on Wednesday.

The ninth-seeded Wozniacki, who has never fared very well on the London grass, is going through a mediocre season. She also lost in the 2nd round at the French Open.

The 196th-ranked Cetkovska, who reached the fourth round at Wimbledon two years ago, erased the six break points she faced and hit 30 winners.

A qualifier from the Czech Republic, Cetkovska's 2012 was cut short after the London Olympics because of a right ankle injury. She returned this year and has nosedived in the WTA rankings.

Sixth-seeded Jo-Wilfried Tsonga of France stopped playing while trailing Ernests Gulbis of Latvia two sets to one after having his left leg treated by a trainer, one of a series of player injuries at Wimbledon on Wednesday.

The 39th-ranked Gulbis was leading the second-round match 3-6, 6-3, 6-3 when Tsonga quit. Tsonga was the runner-up at the 2008 Australian Open and a semifinalist at the All England Club each of the past two years.

Following the second set, Tsonga sat on the grass while a trainer wrapped tape below his left knee.

Canadian teenager Eugenie Bouchard picked up the biggest victory of her career at Wimbledon on Wednesday, beating 12th-seeded Ana Ivanovic, the 2008 French Open champion, 6-3, 6-3 to reach the third round.

The 66th-ranked Bouchard, who is 19, won the girls' title at the All England Club a year ago.

Playing in only her second Grand Slam tournament, Bouchard wound up on Centre Court because her match against Ivanovic was moved there after second-seeded Victoria Azarenka withdrew with a knee injury, leaving a gap in the schedule.

Already leading 5-3 in the first set, Bouchard took 12 of 13 points to close that set and go up a break in the second.

In eight previous Wimbledon appearances, Ivanovic only once had failed to reach the third round.