WIMBLEDON, England

Top-seeded Maria Sharapova was knocked out of Wimbledon on Monday, losing 6-4, 6-3 to Sabine Lisicki in the fourth round just a month after completing a career Grand Slam.

Lisicki, a 15th-ranked German, outplayed the 2004 Wimbledon champion in the wind and rain on Court 1 for her first career victory over Sharapova in four matches. She avenged last year’s loss to Sharapova in the Wimbledon semifinals.

Also advancing were four-time winner Serena Williams and defending champion Petra Kvitova, but four-time Grand Slam champion Kim Clijsters lost in what she says is her final Wimbledon before retirement later this year.

In men’s play, six-time champion Roger Federer was the first to reach the quarters, overcoming an early back problem to beat Xavier Malisse 7-6 (1), 6-1, 4-6, 6-3 and extend his record for most consecutive Grand Slam final-eight appearances to 33.

Federer said his back started hurting in the first few games of the match but he felt much better after taking a medical timeout and receiving treatment.

Sharapova, who won the French Open four weeks ago for her fourth Grand Slam title, is the biggest name knocked out of the tournament since two-time men’s champion Rafael Nadal was upset last week by Lukas Rosol.

After smacking a second-serve ace of 108 mph down the middle on her third match point, Lisicki collapsed to her knees on the grass and shook both fists. Among those cheering for Lisicki in the guest box was German NBA star Dirk Nowitzki of the Dallas Mavericks.

Sharapova was trying to become the first woman since Serena Williams in 2002 to win the French Open and Wimbledon in the same year.

Lisicki will next face fellow German and No. 8 Angelique Kerber, who drubbed Clijsters 6-1, 6-1. The 47th-ranked Belgian has said she is retiring after this year’s U.S. Open — this time for good, having returned to the sport in 2009 after a two-year break. Clijsters, who has been dogged by injuries this year, walked off Court 3 with a brief wave. Third-seeded Agnieszka Radwanska also advanced, beating Italian qualifier Camila Giorgi 6-2, 6-3.

Leading Malisse 4-3 in the opening set, Federer called for a medical timeout and left Centre Court with the trainer for treatment in the locker room. When play resumed eight minutes later, Federer didn’t seem visibly affected — although the speed on his first serve lacked its usual velocity.

Still, in the final game, Federer hit two serve winners and closed the match with a 122 mph ace. He’ll next play Mikhail Youzhny, who beat Denis Istomin of Uzbekistan in five sets.

The sixth-seeded Williams won the last three games of the final set to beat 65th-ranked wild card Yaroslava Shvedova of Kazakhstan 6-1, 2-6, 7-5, in cool and gusty conditions on Court 2.

Williams hopped in joy with both feet in the air after hitting a big forehand that forced an error by Shvedova on the first match point, ending a hard-hitting contest that lasted nearly two hours.

“I didn’t want to lose today and I thought, ‘Just stay relaxed,”’ Williams said. “I knew the whole match I could play better.”

Williams will next face Kvitova, who rallied from a set and a break down to beat former French Open champion Francesca Schiavone 4-6, 7-5, 6-1 in an error-strewn match on Court 3. It was the second straight tough three-setter for Williams, who won 9-7 in the third to beat Zheng Jie in the third round.

The match ended in a slight drizzle, with play suspended on some of the other courts. Shvedova removed her glasses in the final two games to keep the lenses from getting wet.

“I think we both wanted to keep playing because it was so deep into the match,” Williams said. “I didn’t want to stop.

Williams finished with 35 winners, including 12 aces, and 13 errors. Shvedova had 24 winners and 20 errors.

The first player to reach the quarters was 37th-ranked Austrian Tamira Paszek, who beat Italy’s Roberta Vinci 6-2, 6-2 to reach the final eight for the second straight year.