WIMBLEDON, England -- As the trainer kneaded his fingers deeply into the quadriceps muscles above Rafael Nadal's right knee during a break in the fourth set, the expression on the player's face was grim.
Even when he lost two of the first three sets in a second-round match to Robin Haase, Nadal remained the favorite in many minds to win a second title here at the All England Club.
What are we to think now?
Nadal was pressed to the limit for the second straight match Saturday, but rallied -- again -- to beat determined German Philipp Petzschner 6-4, 4-6, 6-7 (5), 6-2, 6-3. The match ran 3 hours and 45 minutes and, even as Rafa was issuing a relatively restrained punctuating fist pump, the questions began.
Petzschner is a talented shot-maker with a reputation for folding under duress -- and that's sort of what happened against Nadal. Still, the 2008 champion looks more like the player who was beaten in the fourth round of the French Open a year ago and forced to skip Wimbledon when the tendinitis in his knees flared.
There were times in the fifth set when Rafa -- who never thinks any ball is beyond his reach -- stood flat-footed as Petzschner ripped several winners.
Not only did Nadal ask for the trainer for an assessment of his left biceps and forearms muscles in the third set, but the fourth-set massage triggered all kinds of fears that Rafa's monstrously physical game had exacted another price. Do not forget that he retired in the third set of his Australian Open quarterfinal match with Andy Murray with a right knee injury. This would have made him two for three.
Afterward, Nadal admitted he was concerned.
"Sure, I am a little bit scared about the knee," he allowed. "But, you know, it happen. I had a treatment after Monte-Carlo. So I had the problem. I didn't say anything before. I had the problem against Roddick in the semifinals of Miami.
"I don't like to say nothing in that moment because when you lose, always looks like an excuse. But I can say now I had the problem after I played in Monte Carlo with a little bit of pain on the knee, on the left knee. After Monte Carlo, I didn't play Barcelona because I had to do a treatment."
Was Rafa really hurt?
Boris Becker, in the BBC commentary box, questioned whether Nadal was seriously hurt. So did U.S. Davis Cup captain Patrick McEnroe after Nadal broke Petzschner by running down two balls in breathtaking fashion in the fourth game of the fourth set for a 3-1lead.
"Nadal breaks injury?" McEnroe tweeted. "Doesn't look like it."
Petzschner seemed to agree with them.
"I thought he was moving great," the German said. "I only could say if I would be injured like this once I would be happy [to be moving that well]. No, but I don't know. Maybe he had something. Maybe it was just a clever part to take a timeout there. I don't know."
Nadal denied that his calls for help were merely gamesmanship.
"Everything is fair to think what they want. I never call the [trainer] when I don't have nothing, not one time in my career. If I call the [trainer] today, it was because it was bothering me a lot, the knee, no?
"The last day, it starts a little bit, and I didn't call the [trainer] because I can't resist that. But today I needed to take little bit time. I have the quadriceps muscle very tight and I need to relax it a little bit. Maybe with this relaxation, the knee works a little bit better."
Not to be outdone, Petzschner called for trainer after the fourth set with what appeared to be a lower back or hamstring injury.
The fifth set -- like Rafa's 6-0, 6-3 conclusion to the Haase match -- was predictably Rafa-centric. A weak backhand service return from Petzschner that drifted wide gave Rafa the match.
And here is the curious thing: For all his apparent physical issues, Nadal hasn't lost at Wimbledon in nearly three years. That was in a five-setter in the final to Roger Federer. Rafa ran the table the next year to win the 2008 title, skipped the tournament a year ago and is now 3-0 heading into Monday's fourth round.
When he won his first Wimbledon title, Nadal had just turned 22 and was playing an ambitious schedule. He won clay-court events at Monte Carlo, Barcelona, Hamburg, Roland Garros and Queen's Club before beating Federer in one of the most memorable Wimbledon finals ever.
This year, as a concession to wear and tear, Rafa elected to skip his beloved Barcelona tournament -- and he went out in the quarters at Queen's Club, which gave him some additional downtime. And yet, he clearly is not 100 percent.
"I'm happy to be in the fourth round," Nadal said. "I'll try to be better for Monday."
Greg Garber is a senior writer for ESPN.com.