Three-time French Open champion Serena Williams withdrew from the tournament Wednesday because of a lingering left Achilles injury.
She made the announcement shortly before her second-round match against Tsvetana Pironkova.
"I really wanted to give an effort here. It's my Achilles that didn't have enough time to properly heal after the [US] Open," Williams said at her news conference. "I was able to get it somewhat better, but just looking long term in this tournament -- will I be able to get through enough matches? For me, I don't think I could. Struggling to walk, so that's kind of a telltale sign I should try to recover."
Williams, 39, said she made the decision to withdraw after trying to warm up for Wednesday's match and feeling like she was moving with a limp.
She said she believes she will require two weeks of rest and four to six weeks of recovery. She said she "more than likely" won't play another tournament this year.
Williams originally suffered the injury during her semifinal loss to Victoria Azarenka at the US Open earlier this month and withdrew from the Italian Open shortly after. She called the injury "bad timing and bad luck" on Wednesday.
The exit extends a Grand Slam drought for the 23-time major champion, who has been looking to tie Margaret Court's all-time record of 24 since winning the 2017 Australian Open.
This is Williams' earliest exit at any Grand Slam tournament since a second-round loss in Paris in 2014 and the second time she has withdrawn from a Grand Slam tournament in her career. Williams withdrew from the 2018 French Open -- her first Grand Slam tournament since giving birth to her daughter -- prior to her fourth-round match against Maria Sharapova, citing a pulled muscle in her chest.
Pironkova, who received a wild card into the event, advances to the third round via walkover. She reached the quarterfinals of the US Open, her first tournament in over three years after childbirth, before losing to Williams in three sets.
Information from The Associated Press was used in this report.