People magazine has reported that tennis star Serena Williams has undergone surgery for a pulmonary embolism.
Spokeswoman Nicole Chabot tells the magazine that the blood clot in Williams' lungs was discovered last week, and that she had "emergency treatment on Monday for a hematoma she suffered as a result" of that treatment.
Williams is being treated at a Los Angeles hospital.
"Doctors are continuing to monitor her situation closely to avoid additional complications," Chabot said.
Williams has been sidelined by two operations on her right foot after getting cut by glass at a restaurant, and has not played a competitive match since winning Wimbledon on July 3.