It will be Li’s second final of 2012 after losing the Sydney championship to Victoria Azarenka. Li beat Sharapova in the semifinals at last year’s French Open, while Sharapova won their last meeting in Miami in March.
Williams has a 17-match winning streak. She had won consecutive titles in Charleston, S.C., and Madrid, plus two matches in Fed Cup.
Williams will move up one spot to No. 5 in the rankings on Monday.
Several other players are also nursing injuries.
Azarenka withdrew with a right shoulder injury before her third-round match. Wimbledon champion Petra Kvitova was bothered by an abdominal injury during a quarterfinal loss to Kerber. And Italy’s Flavia Pennetta retired with a right wrist injury while trailing Williams 4-0 on Friday.
On the men’s side, fourth-ranked Andy Murray skipped last week’s Madrid Open with a back problem and said it was still affecting him after a three-set loss to Richard Gasquet in the third round this week.
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