Wimbledon, July 8 (IANS): Five-time champion Serena Williams fought back from a set down to defeat former World No.1 Victoria Azarenka to set up a mouth-watering women's singles semi-final against old rival Maria Sharapova at Wimbledon here.

Azarenka, a twice Australian Open champion, brought the very best out of herself but still could not stop Williams from entering the last four 3-6, 6-2, 6-3 in front of a crowd of 15,000 on Centre Court on Tuesday, reports Xinhua.

The 33-year-old Williams, who has collected 20 Grand Slam titles, has not been beaten at a Major since she was ousted by Alize Cornet in the third round here last year. She will become the first player since Steffi Graf in 1988 to win all four Grand Slam events in one year if she can pull off the Wimbledon title this year.

Williams has enjoyed a 17-2 record against Sharapova, including 16 victories in a row. The American beat Sharapova four times in the semi-finals at the All England Club. Their last meeting took place in the last 16 of 2011.

"I look forward to it. I don't have anything to lose, I'm just going in there trying to win a match," Williams said of Thursday's match.

No.4 seed Sharapova, who won the title in 2004, dropped the second set but managed to dominate the final one en route to a 6-3, 6-7(3), 6-2 victory over CoCo Vandeweghe, an unseeded American, in two hours 46 minutes. Vandeweghe had never before progressed beyond the third round of any Grand Slam.

"Serving for the second set I could have made it easier for myself. But I still got the job done and I have to be pleased with that and that I'm in a semi-final here again. There's no easy road to victory. You're going to have your bumps. It could have been a two-set match. I made it more difficult for myself but I'm still here," said Sharapova.

The other semi-final will be played between 13th seed Agnieszka Radwanska of Poland and Spain's Garbine Muguruza. Radwanska defeated American 21st seed Madison Keys 7-6(3), 3-6, 6-3 on Court 1 and reached her fourth Grand Slam semi-final.

Muguruza eliminated Swiss 15th seed Timea Bacsinszky 7-5, 6-3 to become the first Spanish woman to make Wimbledon last four since Arantxa Sanchez-Vicario in 1997.

"I always like to take little parts of every player and try to do the same things. You just take a few things and make a perfect player," said the 21-year-old Muguruza, who is the youngest player left in the women's draw.