At this rate, there won't be anyone healthy among top women players at Wimbledon next week.
Caroline Wozniacki retired with a back problem 10 minutes into Friday's semifinal match at the Aegon Eastbourne International, according to Britain's The Guardian.
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Wozniacki is No. 5 in world rankings and is scheduled to face China’s Saisai Zheng on Tuesday in Wimbledon's first round. Play opens Monday at Wimbledon.
This was the latest injury for top women's tennis players. Petra Kvitova, the defending Wimbledon champion, withdrew from the Aegon International because of illness before playing a match. Eugenie Bouchard quit a match as an abdominal injury flared up. Daria Gavrilova withdrew from her quarterfinal against Sloane Stephens.
Ekaterina Makarova, No. 8 in the world rankings, pulled out of her doubles match on Friday because of a left Achilles tendon injury.
Serena Williams is the No. 1 seed at Wimbledon, but her health remains a question. She won the French Open while fighting an illness.