Williams sisters breeze into doubles semi-finals

Defending champions Venus and Serena Williams have breezed into the semi-finals of the women's Olympic doubles thanks to a straight-sets win over Italy's Sara Errani and Roberta Vinci.

The Americans were rarely troubled in the first set as they broke twice to take it 6-1 on Wimbledon's No.2 Court.

It was equally simple in the second as they emphatically booked their place in the last four by winning 6-1.

Next up for the sisters is a semi-final encounter with either Shuai Peng and Jie Zheng of China or Russian third seeds Nadia Petrova and Maria Kirilenko.