WIMBLEDON, England -- Toni Nadal, trudging up the steps from the players' locker room, forced a smile and extended his hand. Twilight was gathering outside at the All England Club and silver stubble was creeping through his weather-beaten face.
After a lengthy rain delay on Wednesday, his nephew and protégé (since the age of four) had utterly embarrassed the remaining British hope, Andy Murray. While Murray seemed baffled -- he called Rafael Nadal's forehand "ridiculous" -- Uncle Toni was wearily but thoroughly happy.
Rafa first came to Wimbledon in 2002 and made it all the way to the semifinals of the junior tournament. A year later, he reached the third round of the main draw at the age of 17. In the intervening five years, he has become the second-best grass-court player in the professional game.
The straight-sets match against Murray, accomplished in less than two hours, was his best grass match ever, Rafa acknowledged.
"Many people say, 'Rafael, his grass game has problems,'" Toni said. "They don't remember he is only 22 years old. Is normal to improve still at this age.
"Give him time."
On Sunday, many here have come to believe, that time will arrive. There is a growing sentiment that Rafael Nadal will end Roger Federer's run of consecutive Wimbledon titles at five.
"Can Nadal beat Federer?" said U.S. Davis Cup captain Patrick McEnroe, laughing. "The question is can Federer beat him? Based on what I've seen so far, I don't think he can beat Nadal."
For a child of clay, born on the Spanish island of Mallorca, grass is a truly foreign surface. While the bounces on clay are generally generous and uniform, the ball skids on grass and stays low. Power is rewarded far more often on grass than on clay. Nadal's prototypical clay-court game -- based on consistent power, defense and attrition -- doesn't necessarily play well on grass.
Just as Federer has struggled to adapt his game to clay -- he's lost to Nadal the past four years at Roland Garros, the past three in the final -- Nadal hasn't quite been able to close the gap on Federer's favored surface, losing in the Wimbledon final the past two years.
Much was made of Federer's desire to beat Nadal in Paris, his passion to prove he is the master of all surfaces. But when Federer won just four games in the final, you got the impression that Nadal, if he's healthy, will never lose a final there to the Swiss No. 1. For the record, he has won 115 of his past 117 matches on clay.
Contrast that with last year's Wimbledon final, when Nadal very nearly beat Federer, losing 7-6 (7), 4-6, 7-6 (3), 2-6, 6-2.
When Nadal won the Wimbledon warm-up tournament, The Artois Championships at Queen's Club, it was the first time in 36 years that a Spanish player won a grass-court tournament. It has been 42 years since Manuel Santana won here at Wimbledon.
"Unlike other Spanish players, he has always believed he can win at Wimbledon," Santana told the Times of London.
Watching Nadal, Santana said, "is like turning on an electric light."
Said John McEnroe, a BBC commentator, "A couple of years ago everybody was asking whether he could transition to winning here on grass. He's come here and improved virtually every aspect of his game -- his serve, court positioning, his backhand and his forehand."
As a left-hander, Nadal enjoys a distinct advantage over his right-handed peers. Everything comes at you from an unaccustomed angle, which only makes Nadal's shots even more effective.
If Nadal's game is passive-aggressive on clay, it has evolved into aggressive-aggressive on grass.
Nadal has grown perceptibly stronger over the past several years, to the point that his biceps have become back-page news among the London tabloids. The muscle manifests itself in raw power. After he was vanquished, Murray called Nadal's ball the heaviest in tennis.
"Yup," Murray said. "He just swings his arm so hard at the ball. When you watch Federer play it looks like he's sort of effortless power. When you see Nadal, how fast he moves the racket through the air, and the amount of spin and speed he generates -- his forehand is the heaviest shot in tennis.
"The ball kind of jumps at a tough angle. It's hard to step into the court and just go for it."
Murray probably doesn't know it, but there is scientific evidence to back this up. Recently, the International Tennis Federation commissioned a study to learn how many times a tennis ball spins on average. While most groundstrokes register in the vicinity of 2,500 rotations, Nadal's ball checks in between 4,000 and 5,000.
On clay, where Nadal's power is blunted, he is content to loop the ball more and outlast opponents. On grass, he has learned to flatten out his shots, and the result is a skidding, deeper ball.
"He's taking the ball early," said Murray. "He's hitting it lower over the net, and playing aggressive from the very first shot, which I don't think he did necessarily in the past."
More depth on groundstrokes means it's easier to play defense. At Roland Garros, Nadal typically plays three feet to six feet behind the baseline. At Wimbledon, Hawk-Eye technology reveals that Nadal has crept to within a foot of the baseline, and as many as one-fourth of his shots are hit from inside it.
"That is the most important thing," said his uncle Toni. "Court position. Before, because he always practiced on clay courts, he was comfortable way behind the baseline. Now, he "
Coach Nadal, struggling for an English explanation, took the writer's pen and drew two diagrams. On clay, it was two arrows, pointing left and right, parallel to and behind the baseline, representing Rafa's defensive track. At Wimbledon, Toni said, the vectors form a "V" at the baseline and indicate Rafa's forward movement.
The biggest area of improvement for Nadal has come on his serve.
In 2003, the average speed of his first serve was a paltry 99 mph, according to IBM statistics. From '05 to '07, he kicked it up to 104 and 105 mph. Through five matches here, he's crushing the ball, averaging 115 mph. Against Murray, his serve brought him all kinds of free points.
And yet, despite the greater degree of difficulty -- and less margin for error -- Nadal's first-serve percentage is 70 -- better than any player in the semifinals, including Federer.
"At Roland Garros he's just pops it in because there's no free points on clay," observed Darren Cahill, the former coach of Andre Agassi and Lleyton Hewitt. "At Wimbledon, he's rewarded for a harder serve. He's hitting his serve harder than he used to, and he's hitting it harder here."
And Nadal isn't just throwing fastballs. He's hitting the black with off-speed stuff, too.
"On clay, 90 percent of the time, he serves it straight into the backhand," said Patrick McEnroe, an ESPN analyst. "Here, he's moving it around to all four corners of the [service] box and both sides of the body."
Nadal is actually serving and volleying, most often on big points, and occasionally, when he serves it out wide, he'll slip into the net when he sees the guy going for a slice.
In the return game, he has become bolder. On clay, he'll return from the baseline or just beyond. In the Queen's final against Novak Djokovic, Nadal usually stood between one and two feet inside the baseline.
Nadal's improved backhand slice has brought another important dimension to his game.
Only one man has managed to win both Roland Garros and Wimbledon in the same summer in the past 38 years. Nadal has a chance to join Bjorn Borg, who did it three years running, in that exclusive club.
A victory could well lead to a change in the 1-2 world order that has ruled tennis for nearly three years. A Nadal win over Federer in the final would leave Nadal with 6,055 points -- just 545 points behind Federer. It would place him in great position to catch Federer as the year unfolds.
If Nadal can break through, Wimbledon would no longer be the exclusive game reserve for Federer. It would set into motion an intriguing swing of the pendulum, for Nadal is just entering the period when great players win the bulk of their Grand Slams -- the sweet spot, if you will.
Federer won 10 of his 12 Grand Slam singles titles between the ages of 22 and 25, and Pete Sampras won eight of his 14 in that same age span. Nadal turned 22 last month in Paris, meaning he essentially has four years to collect some serious hardware. Winning Wimbledon would give him five career Slams and mark him as the favorite for Wimbledon as well as Roland Garros every year.
If he ever concentrates on adapting his game to hard courts, watch out in Melbourne and New York.
Toni Nadal doesn't understand why people have been impatient with Nadal's progression on grass. He correctly points out that Nadal, at 17, was younger than many junior players when he played his first main-draw match here. Juniors face a steep learning curve, the coach reasoned, but because Rafa is under such harsh scrutiny he didn't get the proper time to breathe.
"Rafael learns every year -- because he wants to learn," Toni said. "He wants to be better, and so he has worked hard to do that. I think he can get better."
Greg Garber is a senior writer for ESPN.com.