Serena retires with knee injury against Wozniak

By Matthew Cronin STANFORD, California (Reuters) - Top seed Serena Williams was forced to retire with a knee injury down 6-2 3-1 against Canada's Aleksandra Wozniak in the semi-finals of the Stanford Classic on Saturday. Wimbledon finalist Williams took a medical timeout to receive treatment when she was down 5-2 in the first set, but it made no difference as she was unable to put her weight on her left leg and finally gave up. A disappointed Williams said: "I expected to win this tournament and have a strong start (to the hard court season). "My goal was to win here and I think I would have done it otherwise." Wozniak, who will play in her first Tier II final on Sunday, faces the winner of the semi-final between sixth seed Marion Bartoli of France and Japan's Ai Sugiyama. "It's my biggest final and I'm really happy the way... [read full story]