Summary:
World number two Maria Sharapova is through to the last four of the Aegon Classic in Birmingham.

Full article:
(CNN)  -- Maria Sharapova powered into the semifinals of the WTA tournament in Birmingham with a straight sets victory over old adversary Sesil Karatantcheva on Friday. Sharapova, who is bidding to win her second Wimbledon title, has had to play catch-up at the rain-hit warm-up tournament, which she has won twice. The second seed beat Bethanie Mattek-Sands of the United States and then  fellow Russian Alla Kudryavtseva in straight sets on Thursday and gave Karatantcheva similar short shrift in a 6-2 6-4 victory. The two have history dating back to an on-court incident in 2004 at Indian Wells and Sharapova has easily won their two subsequent matches. Karatantcheva, the 2004 French Open junior champion, was only 16 when banned for two years in 2006 for a doping offence which she vigorously denied. Sharapova is seeded to meet China's Li Na, who beat Kaia Kanepi of Estonia  6-4 6-2, in the final on Sunday. Li will play Aravane Rezai of France, who dispatched Sara Errani of Italy 7-6 7-5. Next up for Sharapova on the grass of the Edgbaston Priory club will be American teenager Alison Riske, who shocked Belgian third seed Yanina Wickmayer 6-7 6-4 6-3 on Friday. Riske had to come through qualifying and survived the loss of the first set on a tiebreak to take charge.