Rafael Nadal refused to retire from his second-round match at the Australian Open despite suffering a hip injury in his shock defeat.
The reigning champion and top seed in Melbourne crashed out on Wednesday, going down 6-4 6-4 7-5 to world number 65 Mackenzie McDonald.
Nadal started sloppily in the first set and then pulled up with an apparent upper leg issue after chasing a forehand at 4-3 down in the second, and his movement was clearly hampered from that point on.
The 36-year-old confirmed he aggravated an issue he had been suffering with for a "couple of days" prior to his meeting with McDonald.
Nadal could well have handed McDonald a walkover, but explained that as defending champion, he did not want to go out without a fight.
"I considered all the time stopping, but I didn't ask," he said in a press conference. "I have to know myself, and I tried to keep playing without increasing the damage.
"I was not able to hit the backhand at all. I was not able to run for the ball. But I just wanted to finish the match. That's it.
"I didn't ask them [his team]. I am old enough to take my own decisions. I didn't want to retire, [as] defending champion here. No, I didn't want to leave the court with a retirement.
"It's better like this. I lost. Nothing to say. Congratulations to the opponent. Just try your best till the end, it doesn't matter the chances that you have.
"That's the philosophy of the sport. That's the essence of the sport by itself. I tried to follow that during all my tennis career, and I tried of course to not increase the damage, because I didn't know what's going on."
Nadal, who is the first top seed to go out in the second round of the Australian Open since Gustavo Kuerten in 2001, is unsure as to the extent of his injury.
"I don't know what's going on, if it's a muscle, if it's a joint. I have history in the hip, I had issues. I had to do treatments in the past," he said.
"Now I feel I cannot move. But I don't know till I do the test and all this stuff, I don't know. I don't know.
"I'm tired of talking about it. I understand, but I lost the match. That's it. I tried until the end. I don't know if in good condition I would win the match. I will have better chances without a doubt."
Nadal added that he would be "lying" if he said he had been mentally destroyed by the issue, given the comfort of his life outside tennis.
However, the 22-time grand slam champion is still motivated to return to the court.
"It's a very simple thing: I like what I do. I like playing tennis," he added.
"I know it's not forever. I like to feel competitive. I like to fight for the things that I have been fighting for almost half of my life or even more.
"It's not that complicated to understand, no? When you like to do one thing, sacrifices always make sense. When you do things that you like to do, at the end of the day, it's not a sacrifice. You are doing the things that you want to do. Sacrifice is when you are doing things that you don't want to do."
The Spaniard conceded another long spell away from the court would be difficult, though.
He said: "Of course it's tiring and frustrating to spend a lot of [this] part of my career recovering and trying to fight against all this stuff all the time.
"I have had seven months playing almost nothing, and then if I have to spend a long time again, then it's super difficult in the end to be in rhythm and to be competitive and to be ready for the fight. Let's see how the injury is, and then let's see how I can manage to follow the calendar."