LOS ANGELES (California), Aug 2: World number one Serena Williams will be unable to defend her US Open title after undergoing surgery on Friday to repair a partially torn tendon in her left knee.

Williams is expected to recover fully from the procedure but will be sidelined six to eight weeks. The US Open, the final Grand Slam of the season, begins August 25 in New York.

Orthopedic surgeon Rodney Gabriel repaired the mid-portion of Williams’ left quadriceps tendon.

“Serena has suffered from quadriceps tendinitis of her left knee for many years, which has been controlled with medication and physical therapy treatments,” Gabriel said. “She recently developed pain that, although improved with treatment, increased whenever she resumes tennis activities.”

Williams has withdrawn from all of her tournaments since winning Wimbledon. She was expected to return just in time for the US Open, an event she also captured in 1999.

“Secondary to an acute injury, an MRI evaluation of her left knee was performed, which demonstrated a partial tear in the mid-portion of her quadriceps tendon,” Gabriel explained.

“Surgical treatment of her partial quadriceps tendon rupture was recommended.”

Williams has won five of the last six Grand Slams and owns a 42-3 match record this season, capturing four of the seven tournaments she has entered. She is a remarkable 34-0 on surfaces other than clay in 2003.—Reuters