Wozniacki spent three weeks out following a similar injury two years ago
World number two Caroline Wozniacki has retired from the Family Circle Cup semi-finals with an ankle injury, but expects to return for the French Open.
Wozniacki rolled her ankle trying to reach the net against Vera Zvonareva in the American city of Charleston.
The 19-year-old said she "certainly hoped" to play the French Open, adding: "Right now, it's not too bad."
At the Barcelona Open, Francesca Schiavone thrashed Roberta Vinci in under an hour to win the title.
Schiavone powered to a 6-1 6-1 victory and the third WTA title of her career against her fellow Italian, who beat her on the way to winning the event last year.
I was surprised that I could stand on my leg, which was very positive, actually
Vinci had won all nine of her previous matches on the Barcelona clay.
"I felt good today," said Schiavone. "I played at a very high level and I was having fun playing. Roberta had some problems with her ankle so it wasn't easy for her. It just wasn't her day."
In the United States, Danish star Wozniacki was 4-2 down in the first set against Russian seventh seed Zvonareva when she suffered the injury.
Wozniacki briefly returned but, after Zvonareva held serve to take a 5-2 lead, she double-faulted at 15-15 and ended her involvement.
She had been seeking her second title in as many weeks, having won at Ponte Vedra Beach last Sunday.
"I was surprised that I could stand on my leg, which was very positive, actually," said the Dane, having explained that she heard a "snap" before feeling pain.
"But as soon as I was moving to the sides, it was impossible, so I couldn't play."
Wozniacki suffered a similar injury to her left ankle two years ago, which kept her on the sidelines for three weeks, but remained confident of appearing at the second Grand Slam of the year, which begins on 24 May.
In the meantime, Zvonareva will face Australia's Samantha Stosur in the final of the Family Circle Cup, after the fourth seed defeated Daniela Hantuchova 6-3 7-6 (7-2).