Kim Clijsters has a torn hip muscle and will need four weeks off the tour.
A statement from her management company on Wednesday said she'd been troubled with hip pains during the Sony Ericsson Open over the weekend in Key Biscayne, Fla. She lost to Belgian compatriot Yanina Wickmayer in straight sets.
Tests show "a small torn muscle" in her right hip, the statement said. She hopes to be back for the Madrid Open, which starts May 5.
Clijsters has said she plans to retire after the summer, highlighting her year with an appearance at the London Olympics.