During the Wimbledon quarterfinals, Nadal would occasionally watch as a ball off the racket of Taylor Fritz landed in.
After taking a medical timeout, Nadal couldn't move the way he normally does. His trademark grunts weren't very common. His serve dipped from a high of 120 mph to barely above 100 mph. He wanted to end exchanges with a quick strike forehand or a drop shot.
With much of the Centre Court crowd loudly supporting the 22-time major champion, roaring and standing after his best strokes, Nadal figured out a way to hang in there.
Nadal wants to add a trophy at Wimbledon to the ones he won at the Australian Open and the French Open this year. He never has won the first three Slam titles of a season.
On Friday, Nadal will meet Nick Kyrgios, an Australian who will be making his Grand Slam semifinal debut after a 6-3, 6-3, 6-7 (5) victory over a player from Chile.
There will be two men's semifinals, one of them will be Novak Djokovic.
Nadal leads the head-to-head series 6-3, but they are even at 1-all at Wimbledon, with Nadal winning the last time they met.
"Obviously, we know that both of them are completely different people," he added. We respect each other a lot. I think that would be a mouth-watering experience for everyone. It would be the most watched match in history. I would make a case for that.
He did not think this day would come. Since 2008, only one unseeded and lowest-ranked man has gotten to the final four at the All England Club, and that was Nick Kyrgios.
I didn't go about things well early in my career and may have wasted a little time. I'm proud of the way I came back out here.
More attention has been given to his behavior on and off the court than his tennis skills. His match against the unseeded Garin came a day after police said that he is due in court next month to face an allegation of common assault.
"I have a lot of thoughts, a lot of things I want to say, kind of my side about it,'' he said after the match. I have been advised by my lawyers that I can't say anything at the moment.
He was fined $10,000 for spitting in the direction of a heckling spectator after his first-round win at Wimbledon. He was fined $4,000 for an audible obscenity after his third-round victory over Tsitsipas.
It's worth noting how well the player has been playing. His serve is one of the best in the game, regularly topping 130 mph, and he hammered 17 ace against Garin in the very first game, at love.
His big forehands are terrific, too, but little else is conventional about the man.
"I don't have a coach,'' he said with a laugh. I wouldn't put that burden on anyone.
The AP contributed.