KEY BISCAYNE, Fla. -- Head down, eyes covered by a white hat, Rafael Nadal played with his phone, oblivious to the commotion all around him.
In the bowels of the stadium at the Sony Ericsson Open on Friday, photographers and reporters zealously jockeyed for position in the interview room, eagerly awaiting the autopsy report of his abbreviated tournament.
Nadal, the No. 2-ranked player in the world, pulled out of his greatly anticipated semifinal match with No. 4 Andy Murray. For about 10 minutes, arms crossed the entire time, Rafa discussed the troublesome left knee that took him out. He grimaced often and pursed his lips; you could actually feel his pain.
"I am not ready to compete," he said, "and I cannot go on court and lie to everybody. That's the thing today.
"Today is bad news, but that's the sport. We cannot expect playing as much as we play, be perfect every day of our life. Today is my turn."
Historically, Nadal is a good soldier, often playing in pain. This is only the second walkover of his career, going all the way back to 2004 in Estoril, Portugal, when he pulled out of a semifinal match with a stress fracture in his left ankle -- an injury that forced him to miss what would have been his first French Open.
This was not a complete surprise, for unlike many professional athletes, Nadal always has been admirably open about his injuries. After visits from the ATP World Tour trainer in his past two matches, he acknowledged the knee was a problem. Consequently, doubts grew about both his mental and physical condition. It's becoming clear that -- given the tendinitis he's chronically suffered in both knees -- the two are inexorably linked.
"Since the beginning of the tournament I have problems, but the real thing is growing worse every day," Nadal said. "So after the last match, I saw that the situation was going to be complicated to play today. But, as always, I always believe that the things can improve.
"I did a lot of treatment yesterday, waiting, that we can recover a little bit for today. I am very sorry for the fans. I'm very sorry for the tournament. But I don't have pleasure."
After beating Jo-Wilfried Tsonga in a grueling quarterfinal, Nadal was laid out flat on his back in the locker room for quite some time as trainers worked feverishly on his knee. On Thursday, he did not practice -- a rarity for Nadal.
Although Nadal spoke optimistically of the strength of his tendons and understanding the kind of treatment necessary to recover, this is only the most recent evidence that he probably will never reach his full potential when it comes to Grand Slam singles titles.
For Nadal is only 25 years old and turns 26 during the French Open. The conventional wisdom regarding his brutally physical game is that Rafa will break down sooner than most players. The torque he generates on his shots, particularly his muscular, sweeping forehand, is enormous and surely challenges his joints, ligaments and tendons. He plays a heavy game at great speed, which has already taken a physical tool. Hard courts, particularly, are, well, hard on his knees.
In 2009, after winning his first Australian Open title, Nadal injured his right knee in Rotterdam. After he lost his first match ever at the French Open (ending a 31-match winning streak), he skipped Wimbledon citing tendonitis. He played the rest of the season, he said, "in very bad conditions a lot of times," referencing an abdominal pull in the U.S. Open.
"Then after U.S. Open I had to stop for one month and a half with no competition," Nadal said. "So I cannot repeat mistakes from the past, but that doesn't mean that I am more afraid about playing with pains or not."
Of course, Nadal rallied in 2010 to win three of the four majors and reclaim the No. 1 ranking.
Although he never conceded he was concerned about his future, this had to be horribly disappointing for Nadal.
Even before this year's Australian Open concluded, he was on record as saying he had plans to take the month of February off. But practicing at home on the Spanish island of Mallorca, he felt twinges in his knee. The pain continued two weeks ago in Indian Wells and gradually worsened.
Next up for Nadal: a trip to the doctor in Madrid, according to Spanish reporters, and a lot of familiar rehab. He said he expected to play in Monte Carlo and Barcelona, which begin April 16 and 23, respectively.
The clay-court season always has been Nadal's safe haven. Last year, he went 25-2 with three titles, losing to Novak Djokovic in the finals of Madrid and Rome. Nadal has won six of the past seven crowns at Roland Garros, but this withdrawal will only heighten the speculation that Djokovic -- in search of his fourth consecutive major -- has a chance to beat him there.
It was a curious sight an hour before the match as hundreds streamed past the palm trees lining the entrance at the Sony Ericsson Open. Some even tried to sell their tickets to incoming spectators who might not have heard the news that the Nadal-Murray match had been canceled.
A few minutes later, Nadal stoically explained his situation.
The last thing he said: "I try my best in every moment with pain, without pain, but when I see the situation is done and I cannot, I cannot," he said. "That's it."