PARIS -- Amelie Mauresmo had an appendectomy and is expected to be sidelined a month.
The fourth-ranked Frenchwoman underwent surgery in Paris. She had a stomachache for several days before a sonogram indicated the need to remove her appendix, her Web site said.
"The operation went well and all that's left for me is to wait patiently," Mauresmo said.
Mauresmo withdrew from the Sony Ericsson Open in Key Biscayne, Fla., shortly before the tournament began Wednesday. Her most recent match was Feb. 24 in the Dubai Open final, which she lost to Justine Henin.
Mauresmo, once ranked No. 1, won the Australian Open in 2006 and beat Henin in last year's Wimbledon final. She hopes to return for the clay-court season.
"The surgeon advised me to walk a bit but not to do anything else," Mauresmo said on her Web site. "I will doubtless need a good month to get all my physical capacities back."