Andy Murray admitted he was moments from quitting during his remarkable victory over Jarkko Nieminen at the French Open and declared: "I can't believe I won".
The world number four woke up on Thursday morning with a back spasm that meant he could not put much weight on his left leg and almost did not take to the court at all for his second-round match on Court Philippe Chatrier.
Murray's troubles became obvious in the fourth game of the match when he was struggling to move and in particular to serve, but he opted to carry on and eventually engineered a barely believable turnaround to win 1-6 6-4 6-1 6-2.
The 25-year-old said: "I didn't find it that satisfying. I just couldn't believe I had won. I guess when you're in that position, especially in a grand slam, emotionally it's pretty challenging, because you're only one or two points away from having to stop.
"I couldn't believe I was in a position to win at the end of the fourth set, so I was starting to get a bit edgy. Rather than it being satisfying, it was just quite emotional."
Murray has been troubled by an ongoing back problem that saw him pull out of the Masters Series event in Madrid earlier this month, but he insisted this was not the same thing, although it may be related.
"Maybe sometimes muscles are doing too much work because you're a little bit weak in that area," he said. "But my physio is one of the best. No doubt about that.
"His advice before the match was that by playing you're not going to do any permanent damage, so go out and give it a go, see how it feels.
"Then obviously it didn't feel good. So they were telling me to stop, and then I just kept going, and then it started to feel a bit better.
"It's one of those things, you can wake up sometimes with a cricked neck or sleeping in the wrong position or whatever. Because I was absolutely perfect yesterday. I had no problems at all."
Murray seemed to be moving a little better and was certainly serving closer to his normal level during the second set, and he managed to retrieve an early break to make it 4-4.
The key game came next, Murray saving three break points as Nieminen pressed hard, and he got his reward as the Finn cracked to hand his opponent a fourth game in a row.
From there, it was virtually one-way traffic. Nieminen, frustrated by his inability to capitalise on such a favourable situation, became increasingly error prone and Murray took full advantage to book a third-round meeting with Colombia's Santiago Giraldo.
Murray was adamant he will be playing that match and is confident he is not risking his health by doing so.
He said: "I'm going to try and carry on regardless, whether it's a bit sorer tomorrow or in two days' time, I'm going to carry on. I'll just try and do all the right things to recover as best as possible.
"I'm not doing myself any actual damage by playing with what I have. I have had all the best advice from some of the top surgeons and physios. I'm confident that I'm doing the right thing."
Nieminen, 30, has had a good season, climbing back inside the world's top 50 and playing some of the best tennis of his career.
He was understandably disappointed with the way he had let a famous win slip from his grasp, and admitted he was surprised Murray was able to complete the match.
Nieminen said: "I tried to concentrate on my game. But the way he was, it looked like he could hardly walk. It looked really bad. It's not often that somebody looks that bad and can keep going.
"(Igor) Andreev retired against me in the first round, and I couldn't see anything until he called the physio to the court. Andy looked way worse.
"Obviously he's one of the best players in the world, and then he's limping and suddenly he's playing again. It's not an easy situation.
"I felt that I should have taken the second set. He still was very off, at least physically very off, for two sets. That's very disappointing. Overall I'm not happy the way I played."
Murray had some sympathy with Nieminen's situation, adding: "I know what it's like playing against someone who is not really moving much. It's not always the easiest thing.
"Then he made some mistakes at the end of the second set, and it was his fault for letting me back into the match because I didn't do anything special. I just tried to put some balls back in."