BRUSSELS, March 28 (Xinhua) -- Belgian tennis star Kim Clijsters will be sidelined for at least four weeks after tearing a hip muscle, her agent said in a statement on Wednesday.

"Kim has got an excess of fluid in her right hip joint, which turned out to be a deep muscle tear in her hip," the statement said.

The former world number one lost to her compatriot Yanina Wickmayer in the last 16 of the WTA tournament in Miami, Florida.

"The pain got worse during the match, making it more difficult for her to move," the statement added.

Clijsters, 28, expects to return to competition in the clay court tournament in Madrid, which starts on May 4.