Andy Murray's Wimbledon run came to a disappointing end with a 6-3 6-4 7-6 (7-2) defeat to Marcos Baghdatis.
The 19-year-old double-faulted to drop serve in the first set and from then on provided little for the crowd to cheer.
From 4-1 ahead, he lost five straight games to concede the second set and, in the searing heat on Centre Court, the Briton's frustration boiled over.
He fought hard to take the third set into a tiebreak but two more double faults all but ended his challenge.
Murray was at a loss to explain his slump in form.
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"It's hard to explain what happened. I didn't feel good the whole match. I tried to get myself going in the third but it didn't happen.
"I don't want to take anything away from Baghdatis but I don't feel like I put up any resistance today."
Murray produced a tenacious performance on Saturday to upset third seed Andy Roddick on Saturday but just two days later, he was a completely different player.
The 19-year-old, playing in the fourth round of a Grand Slam for the first time in his career, looked nervous at the outset.
He had to save a break point in his opening service game and it came as little surprise when he was broken at 1-2, completing a disastrous game with a double fault.
Baghdatis was hardly troubled as he went on to take the set but the Cypriot, who had played so solidly, allowed Murray back in with a host of errors at the start of the second set.
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Murray, without hitting the heights he reached against Roddick, appeared to be finding his feet but another dreadful game at 4-2 proved his undoing.
Two double faults in a row left him 15-40 down and on the first, the teenager belted a forehand way beyond the baseline.
All the while, Murray was intermittently feeling his back, but the trainer never appeared and the teenager later said it had been "stiff" but had not affected his serve or movement.
Baghdatis broke at 4-4 and completed a run of five games on the trot to take a two-set lead.
Murray was beside himself, letting slip an audible expletive as his anger boiled over, but he did at least manage to produce glimpses of his best in the third set.
However, he crumbled in the tie-break, two double faults handing Baghdatis a 4-1 lead and an ace from the Cypriot prompting Murray to scream: "Horrible tennis."
The statistics bore him out, with the 19-year-old committing 21 unforced errors on his way to defeat in less than two hours.