Serena Williams staged a recovery at the expense of Caroline Wozniacki as the American reached the quarterfinals of the Madrid Open 1-6, 6-3, 6-2 yesterday in a battle of former No. 1 players.

The comeback win in 1 hour and 42 minutes put Williams into a showdown with Russian second seed Maria Sharapova, who earned her last-eight place when Czech opponent Lucie Safarova withdrew before their match with stomach illness.

Williams sleep-walked through the opening set as Denmark's sixth seed had it all her own way in half an hour.

After trailing a set and 1-2, the momentum suddenly shifted in the Williams favor, with the ninth seed breaking for 3-2 with a backhand down the line and finishing a run of a dozen points in succession to lead 4-2.

Williams, the 2009 runner-up to Russian Dinara Safina, leveled at a set each and ran off with the third to end with four breaks of serve in a disheartening loss for Wozniacki.

The Dane had been bidding for a sixth quarterfinal of the season. Wozniacki, who won joint WTA-leading six titles in 2011 is still searching for her first of 2012.

In the men's third round on the blue clay of the Caja Magica, Czech sixth seed Tomas Berdych ended the injury comeback effort of Gael Monfils, the No. 12, with a 6-1, 6-1 victory.

The Frenchman was playing for the first time since a March abdominal muscle problem.