A cramp-afflicted Andy Murray lost 7-6 6-7 7-5 to Sweden's Thomas Johansson in a dramatic third-round tie at Queen's.
The 18-year-old Scot had a set point in the first set before Johansson took it 7-1 on a tie-break but Murray fought back to win the second-set tie-break.
The players traded breaks early in the decider and a cramping Murray had to stave off four break points at 3-3.
The teenager then hurt his ankle in a fall and twice received treatment before Johansson finally came through.
The Swede will now play Tim Henman in the last eight after the Briton beat Australian qualifer Chris Guccione 6-7 (4-7) 6-2 6-2.
Murray, who could be heard telling the trainer he heard "something crack" as he fell, could barely run as the match reached its conclusion.
The US Open junior champion is due to play in Nottingham next week before making his debut at Wimbledon.
But he will undergo a scan on Friday to assess the extent of the injury.
"I'm very disappointed," said Murray.
"I played a pretty good match but I'm a bit annoyed I wasn't able to finish it.
"I think I was going to win when I was 30-0 up at 5-4 in the third set.
"When I went over on the ankle I could have got up but I thought I heard something crack so didn't want to take any risks.
Sixth seed Johansson said he had been hugely impressed by his opponent, playing in only his fourth ATP match.
"It was very tough," the former Australian Open champion told BBC Sport.
"I'm very impressed with the way he's playing - especially his serve and his groundstrokes - and he's going to get even better. "
Asked how far Murray might progress, Johansson replied: "We can start with the top 50 for sure. After that, it all depends - he has to work hard."
Henman's match followed Murray's on court and early on, the Briton struggled to find a way to break down the serve of the 6ft 7in Australian qualifier Guccione, who sneaked the first set on a tiebreak.
But Henman broke twice in the second set to take it 6-2.
The British number one held from 0-40 down at the start of the decider and then broke twice again for an ultimately comfortable win.
"I did a great job on my own serve," said Henman, who admitted to having seen a bit of Murray's match.
"He played fantastic tennis and he'll learn a hell of a lot from it," he said.
Henman has never played Johansson on grass but said he was confident in his current form on the surface.
"I feel good about my game at the moment but it's going to be a tough one," said the 30-year-old.