On the eve of the 40th head to head matchup between two of the greatest tennis players of all time Rafael Nadal and Roger Federer, we take a look back at the rivalry that has driven tennis for over a decade.

The theater created between a matchup that consists of 38 major championships and the unquestioned best players to come of their respective countries is palpable.

Tomorrow’s matchup between the two in the Wimbledon semi-final in their first matchup since the two met in the 2008 final at the All England Lawn Tennis and Croquet Club. The final in 2008, is arguably one fo the greatest tennis matches of all-time as the two played the longest championship in Wimbledon history totaling 4 hours and 48 minutes. Nadal’s victory on that evening broke Federer’s Open-Era-record 65-match winning streak on grass.

Nadal was a mere 22 in the final 11 years ago and only held four major championships all happening at the French Open at the time. Critics can point as Nadal being one-dimensional because of this and that he was mortal on other surfaces including grass. The 2008 victory did not necessarily become a breakthrough for Nadal who in the years since has only won 5 other majors outside of Paris.

Some pundits would point to Nadal’s injuries over the years that have slowed his ascent in overtaking Federer and opening the door for another standout player Novak Djokovic to enter the conversation as the best of this era. You have to take into account that legends Pete Sampras and Bjorn Borg only won 14 and 11 majors respectively. Numbers that the big three as they are known as have all surpassed.

The Spaniard is 10-3 in majors against Federer, however only 4-3 when the two do not matchup on clay. The stat shows Nadal’s unquestioned dominance on the surface and why he is the greatest clay-court player ever.

Nadal leads in all of the head to head statistics against Federer going 24-15 head to head, and 14-10 in finals. Once again if you remove the clay-court record, Nadal is not a clear cut better player. Outside of clay surfaces, Federer leads the head-to-head matchup 13-10.

Federer can point at his 0-6 record against Nadal on clay including his recent loss against him in this year French Open as the only blemish on his impeccable record. The Swiss superstar can also make the point that playing on clay in an era against a clay court specialist skews the numbers.

More than half of Borg’s majors took place on the clay surface a total of six. Sampras and Djokovic have only one once in Paris along with Federer. John McEnroe never achieved singles triumph on the Roland-Garros courts. When you remove the tournament from the equation, the numbers show Federer as the best of all-time at least for the moment.

Nadal is attempting with two more victories which likely include defeating his other rival and 15-time major champion and defending tournament champion Djokovic to become within one Federer in major championships. Federer holds the current record of 20 major championship victories on the men’s side.

The debate will rage on after tomorrow’s semi-final, and Djokovic is the number one seed in this tournament, and a win for him this year at Wimbledon would increase the discussion of the greatest ever. Nadal (-140) is the slight favorite in tomorrow’s showdown.