LONDON -- As tumultuous a day as professional tennis has produced in its nearly half-century history ended in the most unforeseeable, unexplainable way of all: A second-round loss by Roger Federer at the All England Club.

The seven-time Wimbledon champion and 17-time Grand Slam champ shuffled off Centre Court with dusk approaching on the fortnight's first Wednesday, his head bowed, his streak of reaching at least the quarterfinals at a record 36 consecutive major tournaments snapped by a man ranked 116th.

His remarkable 6-7 (5), 7-6 (5), 7-5, 7-6 (5) defeat against Sergiy Stakhovsky marked Federer's earliest Grand Slam exit in a decade. He lost in the first round of the French Open on May 26, 2003, back before he owned a single trophy from any of the sport's most important sites.

"This is a setback, a disappointment, whatever you want to call it," said Federer, the defending champion. "Got to get over this one. Some haven't hurt this much, that's for sure."

He had plenty of company on a wild, wild Wednesday brimming with surprising results, a slew of injuries -- and all manner of sliding and tumbling on the revered grass courts, prompting questions about whether something made them more slippery.

Seven players left because of withdrawals or mid-match retirements, believed to be the most in a single day at a Grand Slam tournament in the 45-year Open era. Among that group: second-seeded Victoria Azarenka; sixth-seeded Jo-Wilfried Tsonga; 18th-seeded John Isner, who will forever be remembered for winning a 70-68 fifth set in the longest match ever; and Steve Darcis, the man who stunned 12-time major champion Rafael Nadal on Monday.

"Very black day," summed up 10th-seeded Marin Cilic, who said a bad left knee forced him to pull out of his match.

The third-seeded Federer simply was unable to derail Stakhovsky's serve-and-volley style, breaking the 27-year-old Ukrainian only once.

Still, there actually was a real chance for Federer to get back in the thick of things. Ahead 6-5 in the fourth, he held a set point as Stakhovsky served at 30-40. But Stakhovsky came up with this sequence: volley winner, 111 mph ace, serve-and-volley winner.

In the closing tiebreaker, with spectators roaring after every point, Stakhovsky raced to a 5-2 lead, and the match ended with Federer pushing a backhand wide on a 13-stroke exchange. Stakhovsky dropped to his back, then later bowed to the stadium's four sides. He sat in his sideline chair, purple Wimbledon towel draped over his head, as Federer quickly headed for the locker room. Stakhovsky peeked out and saw Federer leaving, then applauded right along with the fans' standing ovation.

"You're playing the guy and then you're playing his legend," Stakhovsky said. "You're playing two of them. When you're beating one, you still have the other one who is pressing you. You're saying, `Am I about to beat him? Is it possible?"

It was, and Federer was one of seven players who have been ranked No. 1 to depart the tournament in a span of about 8½ hours. The others: Maria Sharapova, the 2004 Wimbledon champion, who lost 6-3, 6-4 to 131st-ranked Michelle Larcher de Brito of Portugal; Caroline Wozniacki; Ana Ivanovic; Jelena Jankovic; Azarenka; and Lleyton Hewitt, who won Wimbledon in 2002.

All told, five players who have combined to win 26 Grand Slam titles headed home, along with another three who have been the runner-up at a major tournament.

Look at it this way: Three days into the two-week tournament -- merely halfway through the second round -- a total of five of the 10 highest-seeded women are gone, as are four of the top 10 men.

The beneficiaries might very well be folks such as defending champion Serena Williams, who most figured might only be challenged in a potential final against Sharapova or Azarenka, and Andy Murray, whose path to Britain's first men's title in 77 years no longer can be blocked by Federer, Nadal or Tsonga.

How, then, to decipher it all?

Let fly with far-flung conspiracy theories.

One hypothesis making the rounds: The grass is different because there is a new head groundsman at the All England Club, Neil Stubley (keep in mind, though, that he's been helping prepare the courts here for more than 15 years, albeit with a less distinguished title).

Another popular idea was that the recent weather -- it's been in the 60s and humid, but without a drop of rain so far -- is affecting traction.

"I don't know if it's the court or the weather. I can't figure it out," said two-time Australian Open champion Azarenka, who said she bruised a bone in her right leg when she slipped on the turf in her victory Monday and couldn't face Flavia Pennetta on Wednesday. "It would be great if the club or somebody who takes care of the court just would examine or try to find an issue so that wouldn't happen."

Tsonga, a finalist at the 2008 Australian Open and semifinalist the past two years at Wimbledon, fell Wednesday and had his leg treated by a trainer, then quit while trailing two sets to one against Ernests Gulbis of Latvia.

Sharapova managed to finish her match, at least, despite losing her footing a few times, but told the chair umpire the conditions were dangerous.

"After I buckled my knee three times, that's obviously my first reaction. And because I've just never fallen that many times in a match before," said the four-time major champion, noting that she thought she might have strained a muscle in her left hip.

"I just noticed a few more players falling a bit more than usual," Sharapova added.

The All England Club took the unusual step of issuing a statement in response to Wednesday's events -- and complaints.

"There has been some suggestion that the court surface is to blame. We have no reason to think this is the case. Indeed, many players have complimented us on the very good condition of the courts," the statement read. "The court preparation has been to exactly the same meticulous standard as in previous years and it is well known that grass surfaces tend to be more lush at the start of an event. The factual evidence, which is independently checked, is that the courts are almost identical to last year, as dry and firm as they should be, and we expect them to continue to play to their usual high quality."

Like Sharapova, Federer will not be among the players who gets a chance to gauge those courts' quality the rest of the way.

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