PARIS: Denmark's Caroline Wozniacki retired from her first-round match against Shelby Rogers in Strasbourg on Monday, throwing her status for the French Open into doubt.
The world number 12 was trailing American Rogers 7-6 (8/6), 1-0 before she was forced to pull out after receiving treatment for a back injury.
Wozniacki, a two-time US Open finalist, missed Roland Garros last year with an ankle problem.
The women's field for this year's tournament, which starts in Paris on Sunday, is already without former champions Serena Williams and Maria Sharapova.