By Martyn Herman

LONDON (Reuters) - Novak Djokovic is fallible after all, as American powerhouse Sam Querrey proved in stunning fashion to stop the Serb's seemingly unstoppable charge toward a calendar year grand slam at a rain-hit Wimbledon on Saturday.

The 28th seed boomed down 31 aces and repelled an attempted Djokovic comeback to win a third-round match that began the previous evening 7-6(6) 6-1 3-6 7-6(5).

Top seed and defending champion Djokovic had trailed by two sets overnight after the Court One clash was stopped by rain on Friday but such is the 29-year-old's aura that most expected him to turn it around, just as he did when faced with a similar predicament against Kevin Anderson last year.

On the resumption, the Serb won the opening four games before another rain delay, but wobbled slightly before securing the third set to halve the deficit.

Djokovic appeared distracted at times, looking up to Boris Becker in his coaching box, but was primed to level the match when he served at 5-4 in the fourth, only for Querrey to break.

When yet another rain delay sent the players off court for an hour with Djokovic serving at 5-6, he returned to take it into a tiebreak.

Querrey went 6-4 ahead and though Djokovic saved one match point with an ace, he shanked a forehand into the tramlines to end his 30-match winning streak in grand slam play -- a run that meant he arrived at Wimbledon holding all four major titles.

Defeat scuppered his hopes of becoming the first man to win all four majors in a year since Rod Laver in 1969 and was his first loss before the quarter-final of a major since the 2009 French Open when he also bowed out in the third round.


"Congratulations to Sam. He played a terrific match," Djokovic said shortly after walking on court. "He serves very well. I think that part of his game was brutal today.

"He just overpowered me."

Querrey was the first American to beat Djokovic in a grand slam since Andy Roddick in 2009 and he will take on Nicolas Mahut of France with a place in a first grand slam quarter-final beckoning.

"It's incredible, especially to do it at Wimbledon, the biggest tournament in the world," said the world number 41 who had lost eight of nine matches against Djokovic.

"I am so ecstatic right now, so happy and that's about it.

"I think that today I played the break points really well. Every time he had a break point I was able to come up with a big serve. And in the end I just fought the tiebreak and got a couple of loose errors and that was it."

After initial nerves on Saturday, Querrey showed great composure, saving 11 out of 12 break points in the fourth set, several with aces, as Djokovic tried everything to take the match into a deciding set.

It looked as though the pressure had told when he dropped serve in the ninth game, but he re-grouped immediately and brought up two break points with a stunning backhand pass.

Djokovic saved the first but scooped a low volley into the net to huge cheers from the crowd.

Querrey held serve before rain returned with Djokovic serving to stay alive. But it could not douse Querrey's fighting spirit as he battled back from 3-1 down in the tiebreak to complete his first victory over a current world number one.

"I had my chances," said Djokovic who confirmed he would not play in the Davis Cup quarter-final against Britain this month.

"I just wasn't feeling the ball as well as I wished."

(Editing by Ed Osmond)