Serena Williams stunned at Wimbledon by German Sabine Lisicki

Serena Williams saw her bid to repeat as Wimbledon champion denied in the round of 16 on Monday by Germany's Sabine Lisiki.

Djokovic, Murray advance on opposite sides of draw

Sabine Lisicki overcome mid-match struggles to earn the biggest win of her career. (Alastair Grant/Associated Press)

Serena Williams saw her match streak end at 34 on Monday, and  more importantly, her bid to repeat as Wimbledon champion.

Germany's Sabine Lisicki topped Williams by scores of 6-2, 1-6, 6-4 on Centre Court, continuing a trend of upsets during the tournament's fortnight. Past Wimbledon champions Roger Federer, Rafael Nadal and Maria Sharapova exited the tournament last week, while top contenders Victoria Azarenka and Jo-Wilfried Tsonga were among a spate of injury casualties.

"I probably couldn't be more disappointed," Williams said. "I think I may have backed off of a success. I was playing something successful. I didn't continue that path. The result didn't go the way it could have gone had I continued to play the way I did in the second set."

Novak Djokovic and Petra Kvitova are the only past Wimbledon winners still in the singles draw.

No. 23 Lisicki get Williams on the defensive with a strong serve and an array of off-speed shots. Lisicki reached the semifinals at the All England Club in 2011 but this will rank as arguably her biggest victory

"I'm still shaking," an emotional Lisicki said in a post-match interview, covering her face with her hands to wipe away tears.

"I'm just so happy."

Lisicki overcame prolonged struggles in the middle of the match, losing nine of 10 games at one point as Williams went up 3-0 in the final set.

Lisicki broke Williams to go up 5-4. She converted her second match point with a forehand winner.

"Serena played a fantastic match," Lisicki said. "She's such a tough opponent. Just an amazing feeling to win this match."

Williams was gunning for a sixth championship at Wimbledon, and 17th Grand Slam title overall.

Lisicki will play Estonia's Kaia Kanepi. Britain's Laura Robson couldn't recover from her missed chances in the first set and fell 7-6 (5), 7-5 to Kanepi.

Women's quarters set

In a busy day at Wimbledon, all remaining men and women were set to play their fourth-round matches.

Djokovic reached his 17th straight Grand Slam quarter-final by beating Tommy Haas 6-1, 6-4, 7-6 (4). He failed to serve out the match at 5-3 in the third and wasted a match point in the next game before closing out the tiebreaker with a forehand winner on his fourth match point.

"I think that I'm playing really, really good tennis at this moment," Djokovic said. "Maybe even better than back in 2011 when I won this tournament."

Djokovic moved on to No. 7 Tomas Berdych, who reached his first Wimbledon quarter-final since he was the runner-up in 2010 by beating Bernard Tomic 7-6 (4), 6-7 (5), 6-4, 6-4. Berdych beat Djokovic in the semifinals that year.

Andy Murray will take on Fernando Verdasco of Spain next after getting the better of No. 20 Mikhail Youzhny of Russia by the count of 6-4, 7-6 (5), 6-1. Verdasco defeated Frenchman Kenny De Schepper 6-4, 6-4, 6-4.

Murray, facing the ever-increasing pressure to become the first British man since Fred Perry in 1936 to win Wimbledon, was in trouble in the second set. He trailed 5-2 against Youzhny, but broke back when the Russian served for the set at 5-4. Then, down 5-3 in the tiebreaker, Murray took the set's last four points. He broke immediately in the third, and cruised from there to set up a meeting Verdasco.

Kvitova became the first player to reach the quarter-finals at Wimbledon, beating Carla Suarez Navarro of Spain 7-6 (5), 6-3.

She was joined minutes later by her next opponent, Kirsten Flipkens. The Belgian, who reached her first career Grand Slam quarter-final by ousting Flavia Pennetta of Italy 7-6 (2), 6-3 — a year after her ranking plummeted as low as 262nd because of injuries.

Former French Open champion Li Na and 20-year-old Sloane Stephens of the United States also entered the final eight at Wimbledon.

Li is a Wimbledon quarter-finalist for the third time in her career when she won a matchup of 30-somethings, routing Roberta Vinci of Italy 6-2, 6-0. Li is on to meet No. 14 Agnieszka Radwanska of Poland, who rallied to beat Tsvetana Pironkova of Bulgaria 4-6, 6-3, 6-3.

Stephens reached her second Grand Slam quarter-final of the year, beating 19-year-old Monica Puig of Puerto Rico 4-6, 7-5, 6-1 Monday at Wimbledon. Next for Stephens in her second appearance at Wimbledon is a match against No. 15 Marion Bartoli, the 2007 runner-up. Bartoli downed 104th-ranked Karin Knapp of Italy 6-2, 6-3.

Tennis history for Poland

Poland will send two men into the Wimbledon quarters for the first time after 24th-seeded Jerzy Janowicz and 130th-ranked Lukasz Kubot each won five-set matches Monday.

They'll play each other Wednesday with the winner becoming the country's first Grand Slam semifinalist.

The big-serving Janowicz reached as high as 137 mph while outlasting Jurgen Melzer 3-6, 7-6 (1), 6-4, 4-6, 6-4, while Kubot defeated Adrian Mannarino 4-6, 6-3, 3-6, 6-3, 6-4.

The last Polish man to make the quarterfinals at a major was Wojtek Fibak, who advanced that far at the last three Grand Slams of 1980.

Playing with his left knee heavily taped following a scary fall in the previous round, Juan Martin del Potro didn't let it slow him down as he beat Andreas Seppi 6-4, 7-6 (2), 6-3 to reach the quarters.

Del Potro twisted his left ankle and hyper-extended his knee during the third set of his win over Grega Zemlja on Saturday, and said he has been icing the knee constantly since.

He said "it's really painful," but that "the doctors are helping me" stay fit enough to play.

The eighth-seeded Argentine converted only two of his 11 break points and needed four match points to close out Seppi, saying he got a bit nervous toward the end.

He will face fourth-seeded David Ferrer in the quarters. The fourth-seeded Ferrer overcame a slow start with a 6-7 (3), 7-6 (6), 6-1, 6-1 victory over Ivan Dodig of Croatia.

With files from