Doubles schedule burdens Williams

Serena Williams must hope the effort of playing two doubles matches in a matter of hours does not take a heavy toll as she tackles Victoria Azarenka in today's Wimbledon semi-finals.

Together with sister Venus, Williams returned to Court Two yesterday to finish off a rain-delayed second-round clash against Russians Maria Kirilenko and Nadia Petrova, and the pair then played a full match on the same court against fellow American Bethanie Mattek-Sands and India's Sania Mirza.