BEIJING, Sept 24; Wimbledon champion Maria Sharapova set up an intriguing semifinal showdown with fellow Russian Svetlana Kuznetsova at the China Open after her opponent Jelena Jankovic retired hurt on Friday with an ankle injury.

Serena Williams progressed to the last four when her opponent, Russian Nadia Petrova, also quit with a sprained ankle. The American top seed will face either Vera Zvonareva or Anabel Medina Garrigues.

Kuznetsova beat Argentine Gisela Dulko 6-4 6-2 in the only match to go the distance. Third seed Sharapova was cruising 5-2 in the first set when Serbian Jankovic took a medical time out before deciding she was unable to continue.

Jankovic, seeded seventh, said she had badly twisted her right ankle during her win over Japan's Shinobu Asagoe. Serena was also in charge of her match and was 6-2 4-1 up when Petrova called it quits.

Kuznetsova produced a performance full of baseline power, strong serving and soft touch as she posted her 13th consecutive victory in just over one hour. Down three break points at 4-4 in the first set, Kuznetsova slammed three winners to get herself out of trouble.

The 19-year-old world number five then broke Dulko's serve to take the set. Dulko wilted in the second set under Kuznetsova's relentless pace and meekly ended the match with a double fault.

RESULTS: Maria Sharapova bt Jelena Jankovic 5-2 (Jankovic withdrew due to injury); Svetlana Kuznetsova bt Gisela Dulko 6-4, 6-2; Serena Williams bt Nadia Petrova (6-2, 4-1 (Petrova retired) Vera Zvonareva bt Anabel Medina Garrigues 6-2, 6-. -Agencies