Intro:

Serena Williams reached the semi-finals of the Madrid Open for the first time in her career after claiming a seventh successive win over Maria Sharapova.

Top seed Victoria Azarenka also advanced along with Agnieszka Radwanska and unseeded Czech outsider Lucie Hradecka.

Script:

Quarter-finals day at the Madrid Open with world number one Victoria Azarenka taking on Li Na in the opening match on centre court.

The Belarussian struggled on serve in the early stages and China's Li took the first set 6-3.

But Azarenka, who is seeking her fifth title of the season, rediscovered her form to level the match before taking the third set.

She will face Agnieszka Radwanska in Saturday's semis after she put out American Varvara Lepchenko.

The Pole had beaten her opponent in both of their previous meetings and it was the same story here, with a 6-4, 6-4 victory.

However, it was not quite as easy as it looked, the match lasting an attritional 1 hour and 43 minutes.

Back on centre court, number two seed Maria Sharapova was up against Serena Williams, two players with 18 Grand Slam titles between them.

Ninth-seeded Williams may have struggled against Caroline Wozniacki in the previous round, but blitzed the number two seed, taking the first set 6-1.

Sharapova showed a little more fight at the start of the second, but still lost the set 6-3.

Williams has now won all 11 matches she has played on clay this year:

"Yes, definitely (the surface) making you have to move but you have to be super quick to move on this court, but yet you have to know how to slide and know how to play clay court tennis."

The number nine seed will take on the winner of the day's last quarter-final, between Samantha Stosur and Lucie Hradecka.

The US Open champion becoming the latest victim of the Czech qualifier.

The Australian going down fighting, eventually losing 6-7 6-7.