(CNN) -- Belarussian Victoria Azarenka has pulled out of next week's star-studded Family Circle Cup tournament in the United States with a shoulder injury.
Azarenka shows her delight after beating Serena in the final at Key Biscayne.
Azarenka, who beat world No.1 Serena Williams to win the Sony Ericsson Open at Key Biscayne on Saturday, said in a statement released by organizers that she was "really sorry" that she would not be able to compete because of a problem with her right shoulder.
The straight sets victory over Williams in the WTA Top Tier event saw the 19-year-old climb to a career-high eighth in the world rankings after her third tournament victory of 2009.
Williams, who is the defending champion at the Family Circle Cup, played the final in Miami with a heavily-strapped left thigh, leading to fears that she too would skip next week's event.
Williams, who beat Vera Zvonarava to win last year, would lose valuable ranking points as she bids to stay world number one if she could not compete.
Her sister Venus and world number three Elena Dementieva are other star attractions in the line-up for the tournament which sees the players revert to clay courts ahead of the French Open in Paris next month.
Indian Wells winner Zvonareva and fellow-Russian Nadia Petrova are also in the field with the $1 million tournament starting with qualifying on Saturday.