The 39-year-old had been scheduled to play her second-round match against Bulgaria’s Tsvetana Pironkova on Wednesday, BBC Sport reported.

The American has won 23 Grand Slam singles titles and was aiming to equal Margaret Court’s all-time record of 24.

“I think I need four to six weeks of sitting and doing nothing,” Williams told a news conference.

“I have been struggling to walk so that’s a telltale sign that I should try to recover.

“Achilles is an injury you don’t want to play with – I think it was one of the worst, don’t want to get to that point, I want it to get better.”

Williams picked up the Achilles problem during her US Open semifinal defeat by Victoria Azarenka earlier this month.

On Monday, she beat fellow American Kristie Ahn 7-6 (7-2), 6-0 in the first round at Roland Garros, but said she was struggling physically.

“In the second set I felt I needed to walk with a limp,” Williams added. “I had to focus on walking straight so I wasn’t limping. I tried and always give 100 percent, I take solace in that.

“I’m not sure I will play another tournament this year. It is not an acute injury, it is a nagging injury. I ran into bad timing and bad luck really.”

Williams won the French Open in 2002, 2013 and 2015 and is currently ranked ninth in the world.

Unseeded Pironkova, 33, moves into the third round of the French Open for only the third time.

Nadal marches on

Rafa Nadal continued his quest for a record-extending 13th French Open title with a 6-1, 6-0, 6-3 crushing of American Mackenzie McDonald to advance into the third round on Wednesday.

The Spanish second seed, also looking to equal Roger Federer’s men’s record of 20 singles Grand Slam titles, was never bothered on court Philippe Chatrier, Reuters reported.

“My objective is to play as well as I can. It was a good match for me today. I’m very happy,” said Nadal.