WIMBLEDON, England -- A decade ago, Roger Federer was not yet the greatest tennis player who ever lived. He was a moody, self-absorbed 15-year-old who didn't like to train and was unmercifully hard on himself.
In a new biography, "The Roger Federer Story: Quest for Perfection," author Rene Stauffer describes his first meeting with the temperamental Swiss star-to-be at an obscure junior tournament in Zurich:
"He was a hot-head. On this September afternoon, his temper exploded even from the smallest mistakes. On several occasions, he threw his racket across the court in anger and disgust. He constantly berated himself. 'Duubel!' or 'Idiot!' he exclaimed when one of his balls narrowly missed the line. He sometimes even criticized himself aloud when he actually won points but was dissatisfied with his stroke."
Later, Federer revealed to Stauffer the mind-set that would propel him to the world's No. 1 ranking.
"I know that I can't always complain and shout because that hurts me and makes me play worse," Federer said. "I hardly forgive myself on any mistakes although they're normal.
"One should just be able to play a perfect game."
In his mind -- more than his dazzling forehand or unfathomable hand-eye coordination, this is Federer's most dangerous weapon -- he probably will never be perfect. But in the context of men's tennis, he is pretty damn close. Playing on grass, he might just be there.
On Thursday, Federer won his 50th consecutive match on grass, 6-2, 7-5, 6-1. Juan Martin del Potro, an 18-year-old Argentine, is a fabulous prospect who hits service bombs. But in the handful of moments that mattered, Federer raised his game into ethereal mode.
The last time Federer lost a match on grass was five years ago; qualifier Mario Ancic dusted him in straight sets. Since then? Perfect.
Federer is on course to win his fifth consecutive Wimbledon title, something only three other men have achieved. Bjorn Borg -- the only player to do it in the Open era, which goes back to 1968 -- won here from 1976 to 1980. Borg, it should be noted, had the previous record with 41 straight grass-court wins.
At Wimbledon, Federer has won 29 consecutive matches, dropping only five sets, and he hasn't been extended past four sets during that span.
When Federer, citing fatigue, withdrew from the Halle tournament, it marked the first time in his career that he has played here without a grass warm-up tournament. Skeptics wondered whether it was a wise choice, but Federer insisted that his back and groin were sore and that he wasn't going to let superstition compromise his chances here.
"I mean, I've got to win the tournament to really prove that my decision was the right one," Federer said after his first-round victory over Teimuraz Gabashvili. "Only that one is going to be good enough for me and everyone else, too."
Last year, sponsor Nike created a cream-colored sports jacket Federer wore entering and departing the court. This season's swinging fashion statement -- perhaps second only to Maria Sharapova's Swan Lake-inspired dress -- is the matching Fred Perry-era trousers. When Federer peeled the pants off after warming up, the crowd at Court 1 cheered.
The truly breathtaking thing about Federer is his ability to summon excellence pretty much at whim.
Take this point in the last game of the first set: Del Potro hit a big cross-court forehand, and Federer had to run flat out to get there. Just as he neared the ball, Federer launched himself into the air, extended his racket and waited a fraction of a second before flicking a cross-court forehand winner. Most players wouldn't have reached the ball at all, but Federer managed to put considerable English on the ball.
In the second set, after del Potro had earned his first break point of the match, Federer erased it with another cross-court forehand winner. He won the game by racing to net and, when most players would have waited for the short ball from del Potro to bounce, Federer -- facing a far greater degree of difficulty -- cracked a wicked backhand swinging volley. Later, Federer had the nerve to hoist a well-disguised volley over the head of the 6-foot-5 player for yet another winner.
It was a momentous day in England. British Prime Minister Tony Blair formally tendered his resignation to the queen and Gordon Brown ascended to the position of power he has coveted for so long.
For Federer, there is no successor in sight.
Greg Garber is a senior writer for ESPN.com.