PARIS — Rafael Nadal is righthanded but swings a tennis racket with his left. He’s among the fastest men in tennis, yet no one would dare call him graceful: When Nadal scrambles for a ball on clay, his feet carve a canal through the dirt. His technique, on all strokes, might charitably be described as awkward — herky-jerky on the forehand, with the racket traveling up as much as forward and his shoulders flying open, and abbreviated and violent on the backhand, as a baseball player might look if he prepared to bunt and then, at the last second, decide to hack away.

Pretty Nadal isn’t. Yet perfect, at the French Open, at least, the twotime-defending champion remains. The 21-year-old Spaniard returned to the semifinals yesterday with a 6–4, 6–3, 6–0 victory over fellow Majorcan Carlos Moya. Nadal’s never lost at Roland Garros in 19 tries, and odds are that won’t change when this tournament ends. Nadal was tired in Hamburg late last month, and he struggled earlier in this tournament, despite not losing a set. As the most important, and perhaps the most challenging, weekend of his young career approaches, however, he’s rounding into form.

“Two days ago and today I play good matches,” he said, referring to his straight-sets victory over Lleyton Hewitt in the fourth round. “And I feel better, because I feel I can play little bit different. I can play a little bit more aggressive.”

The traditional view has it that this French Open is more important to Roger Federer’s legacy than it is to Nadal’s. If Federer wins, he’ll have won all four majors, hold all four of those titles at the same time, and have a very good chance of winning the calendar-year Grand Slam for the first time since Rod Laver in 1969. He would, to many, be the best player in history, at age 25.

There’s a lot at stake for Federer, no doubt. But for Nadal, there’s more. Only one man, Bjorn Borg, has won three consecutive titles at this tournament since it began accepting international players in 1925 (Borg won four, from 1978 to 1981, following his victories in 1974 and 1975). Many tennis greats have dominated during one stretch or another at Wimbledon, as Pete Sampras and Borg once did, as William Renshaw did from 1881 to 1886, and as Federer does these days (he’s won the last four). The French Open offers more opportunity for upsets: More tricky bounces, long, strength-sapping rallies, and more chances for one’s mind to wander.

Consider all the great clay-court players in recent years who could not achieve what Nadal might this weekend. Jim Courier won backto-back titles; so did Sergi Bruguera. Neither man won again. Gustavo Kuerten won in 1997, 2000, and 2001. Ivan Lendl won in 1984, 1986, and 1987. Mats Wilander won three times, though never in consecutive years.

I mentioned technique earlier not to denigrate Nadal, but to highlight that in tennis, and on clay especially, technique so rarely carries the day. For teaching forehands, backhands, and serves, Nadal remains among the worst role models in game. When it comes to concentration and competitive spirit — what Nadal in his limited but effective English so often calls “mentality” — he’s rightly considered the strongest player on the tour. On clay, it’s mentality, not mechanics, that matters most.

Nadal will have to work hard in the next few days to preserve his reputation. On Friday, he’ll play Novak Djokovic, the expressive and confident Serb who reached his first Grand Slam semifinal yesterday with a 6–3, 6–3, 6–3 victory over Igor Andreev. Djokovic’s game has few weaknesses, and he beat Nadal earlier this year in Miami, on a hard court. Unlike Federer, whose backhand often goes kaput against Nadal, Djokovic would prefer to hit his two-handed stroke and won’t be as troubled by Nadal’s high-bouncing forehands. Of the talented youngsters on the tour, Djokovic, 20, is the only one who likes his chances no matter the opponent.

In the final, Nadal would face either Federer, who beat him for the first time on clay in the Hamburg final, or Nikolay Davydenko, who pushed Nadal to three sets in the Rome semifinals. Federer has played a few loose sets this tournament, but when he’s played well, he’s looked, as always, formidable. Davydenko’s form has been impeccable — few men strike the ball as cleanly as the 26-year-old Russian, who remains one of the most underappreciated players on the tour. In the fourth round here, he defeated David Nalbandian, last year’s semifinalist, in four tough sets, and followed it up by bruising Guillermo Canas in straight sets in the quarterfinals. Davydenko hasn’t beaten Federer in eight chances, but this match should more resemble his four-set loss at last year’s Australian Open than his straight-set defeat in the U.S. Open last September.

If Federer comes through, ask yourself: Can he defeat Nadal twice in a row on clay? The world no. 1 played superb tennis in Hamburg, but no one should ever beat Nadal 6–0 on clay, as Federer did in the third set. Nadal had played 19 matches in five weeks when that final began, and he looked listless in the third set. The conditions didn’t help: The players widely consider the balls, and the clay, to be heavier in Hamburg, compared to the faster, higher-bouncing clay courts of Roland Garros. Hewitt, who nearly defeated Nadal in Hamburg, said he couldn’t see anyone solving Nadal here.

“His spin off the forehand, it’s quite amazing,” Hewitt said. “I think the ball was probably in Roger’s zone a little bit more, that hitting zone, especially on the backhand side, in Hamburg. If Nadal uses it right here, I think he’s going to be tough to beat.”

Other than Borg, the French Open has never known a dominant champion. Nadal isn’t the type of player to let that opportunity escape him.

tperrotta@nysun.com