Serena Williams has emergency surgery

A representative for the former world number one and 13-time Grand Slam singles champion said the 29-year-old's recovery is being monitored in hospital.

Nicole Chabot said the American remains at Cedars-Sinai Medical Center in Los Angeles, where she had been having treatment for a pulmonary embolism.

"Last week, Serena suffered from a pulmonary embolism which was discovered upon her return to LA.

"She had been in New York for doctor appointments for the ongoing issues with her foot.

"Doctors are continuing to monitor her situation closely to avoid additional complications."

Williams has undergone two operations on her right foot since it was cut by glass at a restaurant.

She has not played a top-level match since capturing the Wimbledon title last July.

Williams, who ranks sixth among women on the all-time Grand Slam singles title list, has won three US Opens, four Wimbledon titles, the French Open once and five Australian Opens.

The younger sister of fellow tennis star Venus Williams, Serena Williams stretched her stay atop the world rankings to 123 weeks before her limited play contributed to Caroline Wozniacki passing her in October.