Ninth seeded Serena Williams of America extended her unbeaten run on clay to 11 victories as she arrowed 11 aces to down second seeded Russian Maria Sharapova with 6-1, 6-3 scoreline in the quarter-final match of 2012 Madrid Open.

Williams opened the match on strong note and broke Sharapova early at 3-1 and then for the second time at 5-1 before she served out the first set lead in the match.

Match Cast : Serena vs Sharapova

The American broke Sharapova in the first game of the second set but got herself broken in the fourth game to allow Sharapova level the scores at 2-2 in the set. Williams struck for another time at 3-2 and for the final time in ninth game to post a straight set victory.

She will next face the winner of another quarterfinal match to be played between Aussie Samantha Stosur and Czech Lucie Hradecka.