Serena Williams defends Stanford title

Serena Williams has defeated Coco Vandeweghe to retain her Bank of the West Classic title at Stanford, Connecticut.

Despite being broken twice in the opening set, the recently-crowned Wimbledon champion came back to take it 7-5.

The second was more straightforward for the 30-year-old as she broke her fellow American once to win 6-3.

The triumph is Williams's fourth of the year following her victories in Charleston, Madrid and London.