Unseeded American Jamea Jackson beat defending champion Maria Sharapova 6-4, 6-4 on Saturday to become an unexpected finalist at the Birmingham Classic.
Jackson's victory ended the Russian's bid for a third straight title at the Wimbledon warm-up event and was her first win over the former Wimbledon champion after two previous defeats.
In Sunday's final the 81st-ranked Jackson will face Russian Vera Zvonareva, who defeated Meilen Tu of the United States 5-7 6-4 6-3 in the other semi-final.
Until she injured her ankle in practice at the end of April, Sharapova had enjoyed an impressive year, reaching the semi-finals at the Australian Open, winning the title in Indian Wells and then reaching the final in Miami.
Last week, the 19-year-old Sharapova lost to compatriot Dinara Safina in the fourth round of the French Open.
Sharapova will hope to come back to form during Wimbledon fortnight which starts on June 26.