Serena Williams retained her Mutua Madrid Open title and number one spot in the rankings with a straight-sets victory over Maria Sharapova in today's final.

In the battle between the top two players in the world, Williams needed just one hour and 18 minutes to see off the challenge of Sharapova, the American winning 6-1 6-4.

The victory improved the 31-year-old's hugely impressive career record against Sharapova to 13 wins from 15 matches, and also ensured the Russian could not claim top spot in the WTA rankings, which would have happened had Williams lost today.

Williams had dropped just one set in the last seven meetings between the two and Sharapova looked unlikely to improve that record after she was broken three times in losing a one-sided opening set today.

Sharapova, 26, did not manage to fashion a single break point in the first set - compared to five for Williams - but she improved in the second as she capitalised on one of her two break points.

However, that was not enough as Williams broke twice in reply to clinch the match and with it the 50th WTA title of her career - becoming only the 10th woman in history to reach the milestone.