Britain's Heather Watson has moved inside the world's top 40 for the first time, but Laura Robson remains in 43rd position.

Watson, 20, has risen one spot from 40th after a successful year, making it a career best for the Guernsey-born youngster.

Serena Williams, who is currently suffering with a lower back injury, remains in first position, with the only change in the top 10 seeing Petra Kvitova move into seventh ahead of Sara Errani.

For the men, Novak Djokovic remains ahead of Roger Federer and Andy Murray, who sit second and third respectively.