People magazine is reporting that Serena Williams has undergone surgery for a pulmonary embolism- a fancy name for a blood clot in her lungs.
Williams' spokeswoman, Nicole Chabot, says that the clot was discovered last week, and that she had "emergency treatment yesterday ((meaning Monday)) for a hematoma she suffered as a result" of that treatment.
Williams is being treated at Cedars-Sinai Hospital in Los Angeles.
"Doctors are continuing to monitor her situation closely to avoid additional complications," Chabot said.
Serena is looking to get back into playing competitive tennis since cutting her foot on some glass in the middle of last year. Her last match was at Wimbledon last July.
Here's the match we all, probably, will remember her from going forward...