Maria Sharapova will miss the BNP Paribas Open at Indian Wells next week because of a left forearm injury.
The hard-court tournament announced the five-time major champion's withdrawal on Thursday.
Sharapova is currently No. 7 in the WTA rankings. She hasn't competed since losing to Serena Williams in the Australian Open quarterfinals in January.
Williams, who tops the tournament's entry list, got her 18th consecutive victory over Sharapova in the quarterfinals of the Australian Open in January.
Williams says she's ready to win tournaments even if she hasn't played in many recently.
"There's nothing that can stop me right now besides me," she said Thursday.
The 21-time Grand Slam champion has played in just one tournament since mid-September. She sat out the rest of the fall season to rest various injuries after her stunning loss in the U.S. Open semifinals. And she recently pulled out of two events, citing illness.
But the top-ranked Williams looked plenty sharp for most of that one tournament, the Australian Open. She was dominant in her run to the final before she was upset by seventh-seeded Angelique Kerber.
"I was ready to go in Australia," Williams said on a conference call previewing her return to the court next week in an exhibition at Madison Square Garden against good friend Caroline Wozniacki.