Serena Williams has pulled out of the French Open with the foot injury that has sidelined her since last July.
The former world number one and current Wimbledon champion, who won at Roland Garros in 2002, has not played since cutting a foot on broken glass in July.
Williams' sister Venus is a doubt for the French Open as she continues to recover from an abdominal injury.
The 30-year-old, who has pulled out of next week's Brussels Open, has not played since January's Australian Open.
Venus Williams, who retired at the third-round stage of the opening Grand Slam of the season, is yet to decide on whether she will play on the clay courts of Paris.
The Brussels Open is a warm-up tournament for the French Open, which begins on 22 May.
Venus is still scheduled to play at the Aegon International event at Devonshire Park, Eastbourne in June, in preparation for Wimbledon.
Serena said: "While I am making good progress, unfortunately I won't be able to compete in Roland Garros as I am continuing to rehab my foot and recover from the pulmonary embolism.
"I am grateful for every moment I have and the fact that I have returned to the court. I am hopeful that I will be back competing this summer. Thank you all for your continued prayers."
Serena has been replaced in the draw for Roland Garros by Junri Namigata of Japan.
The earlier withdrawals of two-time French Open runner-up Dinara Safina of Russia (back) and Timea Bacsinszky of Switzerland (ankle) meant places in the main draw for Britain's Anne Keothavong and Georgia's Anna Tatishvili.