A few minutes into his quarter-final on Centre Court, Juan Martin del Potro collapsed in agony and it looked as if the tournament was about to see another retirement. Some two hours later, he was prone again, this time celebrating one of the more remarkable victories of this astonishing Wimbledon, having defeated the number four seed David Ferrer 6-2, 6-4, 7-6.
The consensus was that if he got as far as the end of the first set and lost it, he would quit on his chair. Instead, and heroically, he won it 6-2, added the second and then continued serving brilliantly to earn a tie-break and take it with a glorious forehand down the line.
"I was really close to having to pull out," he said later, having got some of his breath back. "It was really painful but the doctor gave me some massive pills. I had the tape, a very tight tape, and that help me to move a little bit, but nothing more. Many things come to my mind, many bad things, but I try to be positive and play unbelievable tennis. I don't want to retire in quarters for first time at Wimbledon. And that's the reason for continuing play. I broke his serve early, and like this that give me confidence to take advantage in the beginning of the match. I think I played my best tennis in this tournament."
Ironically, talk even before the start was whether there would be a match at all after rumours circulated that Ferrer, having only warmed up for a minute or so, then spoken to the doctor, would not appear. He has hardly helped himself this Wimbledon, spending more than 11 hours on court before today - as opposed to Del Potro's eight - because of being unable to win in straight sets and regularly needing tie-breaks to take a set.
Ferrer said he was unable to warm up because of pain in his ankle, but sportingly gave credit to his opponent: "I think he played better than me and deserve to win. He serve very, very good all three sets. Now I need to rest three or four weeks because US season is very important for me."
Even before the match Del Potro had said "the knee is not good," having injured it in taking a fall in beating Andreas Seppi on Monday. It became far worse when his left foot gave way on only the fifth point of the match. The bigger they are, the harder they fall and it is a long way down for the 6ft 6in South American. There followed a long timeout for treatment, Del Potro taking painkillers, which must soon have kicked in as his movement slowly became less restricted.
The pre-match photograph at the net had a Little and Large look to it but after Del Potro's fall the Spaniard must have seen a fourth successive Grand Slam semi-final as only matter of time. Ferrer had won their last four meetings, on three different surfaces, and never ceded a set to the Argentine on grass.
Ferrer, who will be ranked third in the world when the new ATP list is published next Monday, might have been expected to bring his man forward more with drop shots but tried instead moving him around from the baseline and found shots booming back at him. So did the formidable serve of a man nine inches taller, and astonishingly the Argentine was able to break not once but twice in the first set, serving out for 6-2.
The Spaniard's unexpected edginess was reflected when he managed to put his shirt on inside out at the changeover. He began serving more consistently but was then broken by Del Potro's fierce hitting for 4-5 and another set had gone.
With his confidence as well as his knee improving, Del Potro continued serving superbly at up to 129mph. During the tie-break it seemed the weapon might be losing its power at last but after dropping three successive points on it he came through to his first Wimbledon semi-final.