Alison Riske reaches last four of WTA tournament in Birmingham . Russian star sees off Sesil Karatantcheva of Kazakhstan in straight sets . She next faces Yanina Wickmayer of the USA who shocked first seed Maria Sharapova .
Maria Sharapova reaches last four of WTA tournament in Birmingham . Russian star sees off Sesil Karatantcheva of Kazakhstan in straight sets . She next faces Alison Riske of the USA who shocked third seed Yanina Wickmayer .