Charleston: Australian tennis player Sam Stosur retired with a calf injury from her third-round match at a WTA tour event here in South Carolina.
The third seed was Thursday trailing Canadian qualifier Eugenie Bouchard by a set and was 0-2 down in the second when she felt she couldn`t go on.
"I was really excited to get out there and I felt like I played really well - it`s unfortunate that she had to retire," Bouchard said on the WTA website.
In the quarterfinal, the 19-year-old will face ninth seed Jelena Jankovic, who breezed past local youngster Jessica Pegula.
Elsewhere, Swiss World No.63 Stefanie Voegele snatched a comeback 3-6, 6-1, 6-3 win over 10th seed Julia Goerges to book a quarterfinal encounter with Caroline Wozniacki. The second seed Dane didn`t have to uncover her racket Thursday as her third-round opponent Andrea Petkovic withdrew with a calf injury.
The Charleston tournament, known for sponsorship reasons as the Family Circle Cup, is the first WTA clay event of the season and has a prize fund of $750,000.