There’s no doubt that Rafael Nadal, the defending French Open champion, is working harder at this year’s tournament than he did at last year’s.

In the third round, it took him nearly five hours to defeat Paul-Henri Mathieu, a Frenchman with imposing offensive skills who went for broke most of the match. Against Lleyton Hewitt in the fourth round yesterday, Nadal set a furious pace to start, but faced several precarious moments – including a double break point in the critical third set – before prevailing 6-2, 5-7, 6-4, 6-2 in three hours and 17 minutes. Through four rounds at Roland Garros last year, Nadal had played one fewer set and 200 fewer points, and needed three hours and 40 minutes less to do it.

But is Nadal playing worse? Judging by data from his matches, as well as the look of dozens of other matches during a clay-court streak that now stands at 57 consecutive wins, the answer is no. Nadal seems to be playing about the same as he usually does.

Some of the statistics are nearly identical from year to year. Last year through four rounds, he had won 58% of points played. This year, he has won 56% (by the end of last year’s tournament, and two difficult matches against Roger Federer and Mariano Puerta, Nadal’s winning percentage was 56%). This year, he has won slightly more points on return of serve, 48% to 47%. On his serve, he has won 65% of points, compared to 70% at this time last year. He has hit winners on 17% of points and errors on 15%. Last year, those figures were 19% and 13%, respectively.

Other data, however, stands out. Last year at this juncture, Nadal had lost his serve seven times. This year, he has endured 12 breaks of serve, and faced 19 more break points. And this has happened with a better first-serve percentage, 70% compared to 63%.

The reason for this contrast, and the slight declines in the first batch of numbers, has much more to do with how Nadal’s opponents are attacking him. Mathieu and Hewitt have brought a much smarter plan to the court than three of Nadal’s first four opponents last year (for the record, those men were Lars Bursgmuller, Xavier Malisse, Richard Gasquet, and Sebastien Grosjean, the only one to win a set).

One cannot over-emphasize Nadal’s reliance on defense and speed.Yes, he can strike winners from both the forehand and backhand sides, but it’s much more common for his groundstrokes to bounce a little too short inside the court, with plenty of spin and height, as he camps out five feet or more behind the baseline. Nadal spent much of the second set against Hewitt there, and he’s beaten Federer three straight times on clay doing much the same, though the world no. 1 has inched closer to success each time.

Federer tries to negate Nadal’s stupendous capacity to rally by shortening points with aggressive strokes and volleys. Mathieu and Hewitt mimicked this strategy. Mathieu has the firepower to use this tactic to good effect, but not enough consistency. Hewitt cannot supply as much of his own power, and yesterday he missed a few easy volleys that proved costly (six double faults did not help, either). Nonetheless, the ap proach was correct.

Faced with an aggressive opponent, Nadal tends to play more defensively. This was the case in the second set yesterday.

“I was moving backwards,” Nadal said afterward. “It’s something that happens to me once in a while. I’ve got to improve on that.”

Yet despite having the look of a man who had been mauled, Nadal broke serve and took a 4-3 lead before he barely lost the set. Nadal is that good of a defensive player. Hewitt dictated the entire set, serving well, firing forehands down the line, knocking off volleys, and swinging full on his service returns – and he almost lost. Nadal made just 10 errors in 12 games, compared to 11 in the first set, when he controlled the tempo, a sure sign of being on the defensive.

Since he excels so much as a defender, it’s no wonder that Nadal often does not make the most of his offensive skills. His abilities go beyond his highbouncing forehand and a deceptive backhand that he can slug down the line or swing crosscourt with a late flick of his top right hand. Nadal has excellent touch, as he showed yesterday by hitting two consecutive drops shots (one forehand and one backhand) at 2-3,15-40 in the third set.He broke Hewitt at 4-4 with a backhand drop shot that bounced on the sideline and spun away from the Australian.

Volleys are not anathema to him, either. Nadal devotes time to improving his play at the net, and yesterday he hit several fine ones. He could use these skills more, and he probably will have to do so as he ages. He might also learn to vary his left-handed serve, perhaps standing a few steps away from the center mark and hitting more slices, rather than his standard kick.

The rest of this week, Nadal ought to improve the statistics mentioned above. His quarterfinal opponent will be Novak Djokovic, a talented 19-year-old Serb who is just a year younger than Nadal, but 10 years his junior in terms of experience.Djokovic ought to land a few forehand blows before concluding his bestever Grand Slam tournament. From there, Nadal would face the winner of Julien Benneteau, a well-rounded Frenchman having a career tournament, and Ivan Ljubicic, the no. 4 seed but not the best of clay-court players.

When asked yesterday about the 19-year-old French talent Gael Monfils, who fell to Djokovic, Nadal said the athletically gifted Monfils was a more agile, more “spectacular” player. “I have better resistance,” he said.

Nadal often struggles with English, but no better word describes his game. For more than a year, Nadal has resisted all attempts to beat him on clay. He often bends,but never quite snaps. Still, it’s far from certain that resistance will be enough to defend his title in Paris. Against Federer, his likely opponent in the final, Nadal may have to mature quickly and go on the attack.

tperrotta@nysun.com