Serena powers into semi-finals

Defending champion Serena Williams put a firm halt on a run of surprise results at Wimbledon when she beat China's Li Na 7-5 6-3 in their quarter-final.

Serena, seeking a fourth singles title at the All England Club, took to the court knowing sister Venus had lost to Tsvetana Pironkova in her quarter-final, and looked in no mood to follow suit in a high-quality encounter on Centre Court.

Serena took advantage of her only break point in the 11th game before serving out for the opener after 45 minutes, and stormed home in the second, raising her finger to the skies when a Li forehand went wide to give her victory.

She will play Estonian qualifier Kaia Kanepi or Czech Petra Kvitova for a place in Saturday's final.