LONDON - For 34 matches over 4 1/2 months, on hard, clay or grass courts, Serena Williams was unbeaten - and, in the minds of many, unbeatable.
So it was apt, somehow, that the longest winning streak in women's tennis since 2000 would end at this memorably unpredictable edition of Wimbledon, where up is down, where seedings and pedigree mean nothing whatsoever, where even five-time champion Williams looked lost at the start and, most surprisingly of all, the finish of her fourth-round match.
The No. 1-ranked and No. 1-seeded Williams dropped the last four games to bow out 6-2, 1-6, 6-4 Monday against 23rd-seeded Sabine Lisicki of Germany.
"She's human. You cannot be perfect, every match, all year," said Patrick Mouratoglou, the French coach who began working with Williams last year.
Williams had won three of the past four Grand Slam titles, including Wimbledon a year ago and the French Open less than a month ago. But, she said, "I didn't play the big points good enough. I didn't do what I do best."
Oddly passive down the stretch, Williams let Lisicki to do what she does best: dictate points quickly with a big serve, powerful returns and pinpoint groundstrokes. Lisicki compiled a 10-7 edge in aces, a 35-25 lead in winners, and broke Williams five times.
Williams said her serve - usually her main weapon - let her down in the third set.
"I felt that I was on the verge of winning," said Williams, who blew leads of 3-0 and 4-2 in the third set. "At that point, I just was physically unable to hold serve. ...
"(Lisicki) is excellent," Williams added. "She's not a pushover."
Especially on grass. Lisicki is a mediocre 16-15 at the other three Grand Slam tournaments and 17-4 at the All England Club. She reached the semifinals at Wimbledon in 2011, and is into her fourth quarterfinal, beating the reigning French Open champion every time: Svetlana Kuznetsova in 2009, Li Na in 2011, Maria Sharapova in 2012, and Williams in 2013.
"Good omen," Lisicki said.
Williams joined quite a list already gone: Roger Federer, Rafael Nadal, Victoria Azarenka and Sharapova - all former No. 1s.
"This," summed up 17th-seeded Sloane Stephens, "has been a crazy Wimbledon."
Sure has. No U.S. men reached the third round, something that last happened 101 years ago, and Williams' departure made Stephens, 20, the lone American singles player left. Stephens beat 19-year-old Monica Puig of Puerto Rico 4-6, 7-5, 6-1 on Monday.
Stephens' first quarterfinal at the All England Club comes today against No. 15 Marion Bartoli of France, the 2007 runner-up.
The other matchup on their half of the draw is No. 8 Petra Kvitova of the Czech Republic, the 2011 Wimbledon champ, against No. 20 Kirsten Flipkens of Belgium. Today's remaining quarterfinals are No. 4 Agnieszka Radwanska of Poland, who lost to Williams in last year's final, against No. 6 Li of China; and Lisicki against 46th-ranked Kaia Kanepi of Estonia.
Kanepi beat Laura Robson, 19, 7-6 (6), 7-5, the first British woman in the fourth round at the All England Club since 1998.
After losing the first set against Lisicki, Williams won nine straight games to lead 3-0 in the third. The players traded breaks to give Williams a 4-2 lead, but Serena couldn't win another game despite having four break points at 4-3.
Serving for the biggest win of her career, Lisicki double-faulted. But she hit a 113-mph ace and a 99-mph service winner, then ended a 17-stroke exchange with a forehand winner before dropping to her knees as tears flowed.
"I'm still shaking," Lisicki said. "I'm just so happy."
• What: Women's quarterfinals
• When: 4 a.m. (ESPN2); 5 a.m. (ESPN)