There are as many similarities as there are differences between Rafael Nadal and Björn Borg, the legend whose all-time record for  French Open men’s singles titles the Spaniard is attempting to surpass.

Last June, as Rafael Nadal and Roger Federer warmed up for the 2011 men's final on Court Philippe Chatrier in Paris, four former Roland Garros champions strode down the steps behind the north baseline, through the milling crowd, and took their seats in the front row. There was a player for each 10-year anniversary: Manolo Santana, winner in 1961, sat next to Jan Kodes, champ in 1971; in the next seat was Jim Courier, winner in ’91, and to his left was Gustavo Kuerten, the beloved Brazilian who had hoisted the Coupe de Mousquetaires in 2001. From the classily coiffed Santana to the wild-haired Guga, it was an illustrious lineup. But these four legends couldn’t help being overshadowed by their only missing member, and missing year: 1981. Who won the French Open that spring three decades ago? No one should have been surprised to learn that it was Björn Borg, the man whose record six titles Nadal would tie a few hours later.

The Swede had chosen, as he has chosen for the last few years, to save his summer trip down memory lane for Wimbledon, where he took part in anniversary celebrations with his old grass-court rival, John McEnroe. So fans in Paris were left to imagine the sight of Borg, after the match, presenting Nadal with his sixth champion’s trophy. There couldn’t have been a more fitting passing of the torch in sports. Borg and Nadal are tied together not just as fellow French Open champs, clay-court specialists extraordinaire, and No. 1-ranked players, but as the two men who have shown, more than any others in the Open era, what dominance looks like on a tennis court. Who’s the best player ever? There’s no definitive answer, but here’s one that should be considered: If we measure the greatness of an athlete by how difficult it is to beat him, the two greatest tennis players of all time are Björn Borg and Rafael Nadal, on clay.

We can start with their stats, the highlights of which are suitably mind-boggling. Nadal won 81 straight matches on clay from 2005 to 2007, a men’s record for all surfaces; Borg won 46 straight on dirt from 1977 to ’79, third on the all-time list.

Their records are, if anything, even more impressive once they arrive in the capital of clay, Paris. Each won the French Open for the first time at 18; it was Borg’s second trip, Nadal’s first. Borg would go on to win the title six times in the eight years that he played at Roland Garros. The only player to beat him there was Italy’s mercurially talented Adriano Panatta, who did it in 1973 and ’76.

Few believed that any man could match Borg’s 49-2 record in Paris; Nadal himself once dismissed the idea as “almost not possible.” But so far Rafa has done the Angelic Assassin one better. The Spaniard won the first 31 matches he played at the French Open, which brought him four titles. After losing in the fourth round in ’09 to Robin Soderling, Nadal won his fifth and six championships in 2010 and 2011, running his record there to 45-1.

When you look inside those numbers, you find—you guessed it—more dominance from both men. In 1978, Borg won Roland Garros without dropping a set; he lost just 32 games, an Open era record. In the final, he surrendered just four games to another master of clay, Guillermo Vilas. Borg would also win the 1980 French Open without dropping a set. In ’81, Borg was ahead 6-0, 6-0, 5-0 against American Terry Moor in the fourth round when a couple of the Ice Man’s ground strokes uncharacteristically went awry and he lost a game. Moor said afterward that he briefly considered imitating Borg’s famous Wimbledon celebration by dropping to his knees and thanking God. Another opponent of Borg’s said that his mystique was such that you could have propped a cardboard cutout of him up on a clay court and his opponents would have been intimidated by it.

It would be 28 years before another male player would win the French Open without dropping a set. That player was Nadal, of course, in 2008, when he lost just 41 games during the tournament and stamped it with a 6-1, 6-3, 6-0 win over Roger Federer in the final. Nadal would, like Borg, also win the title without dropping a set a second time, in 2010, avenging his only career loss at Roland Garros to Soderling in the final.

You get the picture. These players, in their eras, have taken wholesale ownership of one of tennis’ major surfaces. It makes sense that the surface is clay. It lengthens rallies, takes some of the unpredictability out of the game, and makes the sport a test of speed, stamina and patience. It also makes it harder to knock off the physically superior players, even when they’re having an off day.

It’s no accident, then, that Borg and Nadal were the great physical specimens of their generations. Neither has been considered an artistic champion or touted as a “genius.” That term was reserved for their brilliant rivals, McEnroe and Federer. Borg and Nadal, by comparison, have gotten the short end of the descriptive stick—according to most fans and writers, they aren’t geniuses, they’re “grinders.”

But there are many arts to tennis, and Borg and Nadal each mastered its most fundamental, and thus overlooked, ones. There’s nothing mysterious or supernatural about what they’ve done well. Accuracy, consistency, patience, fortitude—this is what wins matches for many of us, and it’s what has won them for Borg and Nadal on clay. Rather than the elegant one-hander or the feathery drop volley, their specialties are the heavy topspin forehand, the impossible sliding get in the far back corner of the court, and the curling passing shot on the dead run. Nadal and Borg worked for it all.

And they know that better than anyone. Once, at Wimbledon, Borg’s wife, Mariana, made the mistake of looking ahead to his first-round match and telling him that it would be “easy.” The stoical Swede did the equivalent, for him, of hitting the roof—he walked silently out of the room. An hour later, while the two were sitting together, Borg suddenly put down the newspaper and pointedly informed his wife, “I just want to remind you, Mariana, there’s no such thing as an easy match.”

Nadal’s brilliance on clay has also been taken for granted. Listening to some fans, you might think that his speed and strength and stamina give him an unfair advantage on the surface, and his wins in Paris are the tennis version of a jog through the Bois de Boulogne. Don’t tell that to Rafa. This spring he was asked what his favorite memory from Roland Garros was. After talking about how “beautiful” his first title had been in 2005, he went on to describe the struggles and satisfactions that have come with doing it over and over again. “When you have troubles,” he said, explaining why his first win, at 18, wasn’t necessarily his most memorable, “when you have injuries, tough losses, hard times, good times, you really know how tough it is to win another time. When I won in 2010 and 2011, the emotions were high, because you don’t know if you’ll be able to win again, ever.”

Winning what you’re supposed to win: Is there anything more difficult in sports? You might ask the other dominant athletes of recent decades. Bill Russell, Wayne Gretzky, Michael Jordan, Tiger Woods—all of them won, over and over again, yet none did it with the numbing regularity of Borg and Nadal at the French Open. Both players worked hard to make the impossible look routine. But like the aforementioned legendary athletes, there is something spectacular and iconic about seeing these kings on their courts. The main stadium at Roland Garros is the closest thing to a Roman amphitheatre in any sport. The red clay at its bottom seems to go on forever; nowhere else do two players, roaming over all of that ground, look like such lonely warriors. From the bloody color of the court, to the fickle and judgmental Parisian audience, to the three-out-of-five set wars of attrition that must be survived, this can be tennis’ most vicious proving ground.

Borg and Nadal had different ways of proving themselves. The Swede’s downcast eyes and eternally expressionless face; his angelic headband and inward-directed determination; it made him seem impenetrable, an immovable ice block. The Spaniard is the fire to that ice. He walks out, Babolat already in hand. He sprints to the baseline after the coin toss. He grunts with each shot, reveals his cringing anxiety after each miss, and shows his joy with each victory leap.

The two players have been received differently as well in Paris. When Borg won his French Opens, there was a sense in the crowd that his victory meant that all was right in the world again, at least for one day. Last year, when Nadal won his sixth, he received tepid applause; the crowd had been rooting, as they have almost always rooted, against him. The hero and the villain, the Ice Man and the Bull, they’ve found their own ways to tennis perfection on clay.

This spring Nadal will try to break Borg’s record by winning his seventh title at Roland Garros. With Novak Djokovic in the draw, for the first time in seven years, Nadal is arguably not even the favorite. But if Rafa does win, who will the organizers have on site to hand him the trophy? It’s the 30th anniversary of Mats Wilander’s title there in 1982, but there’s only one Swede who makes sense for the job. Borg and Nadal belong on clay together.

Originally published in the June 2012 issue of TENNIS.