No end to Rafael Nadal's upside

When a player turns in the kind of performance Rafael Nadal delivered Monday in the high-quality U.S. Open men's singles final (he blasted Novak Djokovic 6-4, 5-7, 6-4, 6-2), you tend to explore one or both of two themes: character and talent.

But the main theme on the night was that Nadal became just the seventh man in tennis history to accomplish a career Grand Slam (and the youngest career Slammer among the three Open era men who share that distinction: Nadal, Roger Federer and Andre Agassi).

Nadal's triumph was not primarily one of courage, although he played with an abundance of it (as did Djokovic), nor was it one of brilliant shot-making, although we saw enough of that from both men to keep us satisfied until January. It was about the desire of a great and already iconic player to become even better and about the humility that is as formidable a feature of his genius as that signature bolo forehand.

In winning the U.S. Open, Nadal completed a remarkable transformation from a radical clay-court stylist into a man for all surfaces and all majors. He did it with the diligence and patience of a craftsman, rather than an artist, which is the thing that fans of "beautiful tennis" -- the kind Federer plays -- have always held against Nadal.

If you trace Nadal's career, you can almost tick off the improvements he made in his game as if they were the milestones that led him to this historic juncture: the willingness to flatten out his groundstrokes when the surface and occasion demand; the determination to learn to play from on the baseline or just inside the court; the addition of a slice backhand to his repertoire; the realization that the volley can be a useful tool. And finally, the element that did the most to secure his career Slam over two weeks in New York: the decision to make his serve into a weapon.

This guy has worked so hard on his game that you could be forgiven for thinking his name is Andy Roddick. Only he did it, or a lot of it, as the No. 1 player in the world and the nemesis of Federer. What kind of a player stands out as a towering champion as well as a work in progress? The kind of guy who delivered the best quote of the U.S. Open when he said, after his semifinal win, "I don't go to the practice court to practice. I go to the practice court to learn."

Nadal sure was a quick study in New York. Just days before the Open, he tweaked his service grip (drifting a little further over to the eastern) and slightly modified his stance. The result heading into the final? His serve was broken just twice. He almost miraculously added 10 miles per hour to his standard issue first serve and the extra velocity served him well. One of the critical moments of the superb final occurred in the third set when Nadal served for the set at 5-4. He had converted just one break point out of 11, the match hung in the balance and Djokovic's resistance was stiff.

Nadal fell behind 15-30, and let's let him take it from there: "At that very important moment I did something I never did: three serves, once ace and two service winners. So that's the big experience for me and believe me, that's good."

After Nadal won that third set, the handwriting was on the wall. It still is. It reads: "Run for cover, everyone, this guy just keeps getting better."