Serena Williams this week underwent emergency treatment as a result of a blood clot in her lung, according to reports in America.
The 29-year-old's spokesperson released a statement to People magazine confirming she had received treatment on Monday for a haematoma, suffered as a result of a pulmonary embolism which was diagnosed last week.
"(On) Monday Serena Williams underwent emergency treatment at Cedars for a haematoma she suffered as a result of treatment for a more critical situation," Nicole Chabot's statement read.
"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 been out of competitive action since winning Wimbledon in July, her 13th grand slam title.
She subsequently cut her foot on some broken glass, an injury which has required two operations.
Despite her lengthy absence, she is still ranked 11th in the world.
On Sunday night, the day before her reported emergency treatment at Cedars-Sinai Medical Center, she attended the Elton John AIDS Foundation Academy Awards Viewing Party in Los Angeles.