Serena Williams' Wimbledon doubles return with sister Venus is confirmed - but 44-year-old faces battle with knee injury to be fit

Serena Williams and Venus Williams have been officially scheduled to play doubles together at Wimbledon, with their match listed for Saturday's play. However, 44-year-old Serena is battling a knee injury that puts her participation in doubt. It remains uncertain whether the sisters will actually take to the court given her physical condition.