World No. 1 Maria Sharapova and outgoing former top-ranked star Kim Clijsters bowed out of The Championships on Monday, while reigning champion Petra Kvitova and four-time winner Serena Williams moved into the quarterfinals at Wimbledon.

Sharapova was upended by 15th-seeded big-serving German Sabine Lisicki 6-4, 6-3 on Court 1 at the All England Lawn Tennis Club. Lisicki avenged her semifinal loss against Sharapova in the semifinals here a year ago and had been 0-3 lifetime against the tall Russian.

"It's just unbelievable," Lisicki said. "For the third time I've beaten the French Open champion here. I'm just so happy. I've lost the three previous meetings against her. Now I just played well and beat her for the first time."

Lisicki, nicknamed "Boom-Boom" like her fellow German and former men's star Boris Becker, popped six aces, including a match-ending one, and broke Sharapova four times in the 84-minute affair, while the Russian veteran settled for five aces and only a pair of breaks in a surprisingly-easy win for the German.

Sharapova was trying to become the first woman since Williams in 2002 to capture the French Open and Wimbledon in the same year. The Russian star completed a career Grand Slam last month by securing her first French title.

The 25-year-old Sharapova captured her lone Wimbledon championship in 2004, when she beat Williams in the final at the tender age of 17, and was last year's runner-up here to the lefthanded Kvitova.

Sharapova, who could lose her No. 1 ranking this week, was seeking a trip into a fourth major final in her last five tries. In addition to winning the French and losing to Kvitova here last year, the Russian lost to Victoria Azarenka in this year's Australian Open finale.

Meanwhile, a fourth-seeded Kvitova posted her 11th straight victory at the AELTC with a come-from-behind 4-6, 7-5, 6-1 victory over 24th-seeded Italian Francesca Schiavone, the 2010 French Open champ and 2011 Roland Garros runner- up, and a sixth-seeded Williams again went the distance, but again came out victorious with a hard-fought, fourth-round victory over Kazakhstan's Yaroslava Shvedova.

Kvitova got past Schiavone in 2 hours, 39 minutes with the help of 13 double faults from the Italian veteran. The big Czech broke Schiavone four times, while the gritty Italian could manage only two breaks in defeat.

Williams had to rally from a set down to beat China's Zheng Jie in the third round on Saturday, prevailing 9-7 in the decisive stanza, and went deep into the third set Monday to get past Shvedova, advancing to the quarters with a 6-1, 2-6, 7-5 triumph.

The 13-time Grand Slam singles champion Williams and Kvitova will lock horns in the round of eight on Tuesday.

The 30-year-old Williams breezed through the first set on a cold and rainy Monday in 26 minutes, but Shvedova, who played a "golden set" by winning every point in the first set of her third-round win over last month's French Open runner-up Sara Errani on Saturday, had an answer with a dominant second set in 34 minutes.

As rain picked up and other courts stopped play, Court No. 2 remained active and the third set remained on serve until late.

Williams picked up three break points in the ninth game, only to watch Shvedova save all three and hold. In the 11th game, Williams again earned a pair of break points and needed only one to convert when Shvedova's backhand went wide.

Shvedova, though, fought through the next game and thought she'd hit a winner on a brilliant angle that would have given her a break point. Williams, though, ran it down and lifted a perfect lob to instead set up a match point, which she quickly converted by drilling a backhand that went unreturned.

Williams will now appear in a 10th Wimbledon quarterfinal (7-2).

"I didn't want to lose today and I thought, 'Just stay relaxed,'" Williams said. "I knew the whole match I could play better."

Clijsters, unseeded and playing at Wimbledon for the last time, was lambasted by eighth-seeded German southpaw Angelique Kerber 6-1, 6-1 on Court 3. The Belgian wife and mother gave a quick wave to the crowd as she walked off the court to some robust of applause.

Kerber, who has been a rocket on the rise since reaching the U.S. Open semifinals last year, will battle Lisicki in an all-German round-of-eight matchup on Day 8.

The four-time major champion Clijsters went 28-9 in her Wimbledon career, including trips to the semis in 2003 and 2006. The Belgian star never reached a final at tennis' most prestigious event.

The 29-year-old Clijsters will retire from tennis, for a second time, following this year's U.S. Open.

A second-seeded Azarenka reached a second straight Wimbledon quarterfinal by blitzing 14th-seeded fellow former world No. 1 Ana Ivanovic 6-1, 6-0 in 62 minutes. The match was delayed by rain and a roof closure on Centre Court, but the outcome was never in doubt on Day 7.

Ivanovic is a former French Open champ and two-time Grand Slam runner-up.

Azarenka reached her first-ever Grand Slam semifinal here at Wimbledon last year and captured her first career major title at the Aussie Open back in January.

The highest seed still standing here, Azarenka will battle quality grass- courter Tamira Paszek on Tuesday.

Steady third-seeded Pole Agnieszka Radwanska reached the quarters here for the first time since 2009 with a comprehensive 6-2, 6-3 victory over upstart 20- year-old Italian Camila Giorgi.

Radwanska reached back-to-back Wimbledon quarterfinals in 2008 and 2009.

Her quarterfinal opponent will be 17th-seeded Russian Maria Kirilenko, who outlasted 30th-seeded Chinese Peng Shuai 6-1, 6-7 (6-8), 6-3 to reach her first-ever Wimbledon quarter.

The first woman to advance to the quarterfinals Monday was Austria's Paszek, who rolled to a 6-2, 6-2 victory over Italy's Roberta Vinci, the 21st seed. Paszek was a quarterfinalist last year in this London suburb.