There can be little doubt that Rafael Nadal and Björn Borg are the two greatest clay courters to ever play the game (unless your name is Simon Reed and you believe Roger Federer is the second greatest clay courter of all time).
Both of them won their sixth French Open title a few days after turning 25 years old, and both have been extremely dominant on the surface during their time.
But is it possible to declare one above the other?
Nadal is, in many ways, the heir to Borg. Both of them were the fittest and most inexhaustible players on tour, and both of them play with a massive amount of topspin on their forehand (Nadal with a lot more, partly due to technological advances).
Both are also aggressive baseliners, who have managed to transform their clay-court game just enough to conquer the lanes at Wimbledon and be dominant there as well (Borg obviously more).
Borg has 64 titles to Rafa's 46. A little less than half (30) of Borg's titles has come on clay. Seventy percent of Rafa's (32) have come on clay, so Rafa leads Borg by two clay titles.
They are tied at six a piece with regards to the most important trophy, the French Open. But whereas Nadal has only lost once there, in 2009 to Robin Söderling, Borg lost twice to Adriano Panatta in 1974 and 1976.
They are as good as equal in many ways, but, in my mind, what gives the edge to Rafa in the end is his more consistent dominance throughout the years.
Rafa is an astonishing 231-18 on clay, with a win percentage of 92.8 percent. Now that is surface dominance. Since 2005, it's something like 208-8.
Borg has an extremely good 245-39 record (86.3 winning percentage) on clay, but it pales in comparison to Rafa's.
The difference is small, admittedly. To be sure, Borg was a very, very dominant clay champion. In his 1978 French Open campaign, for instance, he handed out two bagels and three breadsticks—in the semis and the final!
Still, he didn't dominate the clay season year in and year out to quite the same extent as Rafa has since 2005, where's he won Monte Carlo each and every year, Barcelona six times, Rome five times, Roland Garros six times and Madrid/Hamburg a combined three times.
So while the race is tight, I will argue that Rafa has already surpassed Borg ever-so slightly, despite still being equal in French Open count.