Rafael Nadal's victory over Roger Federer to win his sixth French Open title once again showed why this rivalry might be the best that tennis has ever seen. 

The rivalry started in 2004, but between 2005-2010, Federer and Nadal finished in the either of the top two spots, and even now, Nadal is #1, while Federer is #3.

During this time, 19 of their matches have been for tournament finals and a record 8 in Grand Slams. 

Nadal leads the head to head match 17-8, but that doesn't diminish Federer, who leads Nadal overall in Grand Slam titles 16-10.

At the beginning of the rivalry, Federer seemed to have the edge on Nadal on everything except clay.  But since the epic 2008 Wimbledon finals which Nadal won, Nadal has turned the tables. 

In fact, the 2008 Wimbledon finals is considered by many to be the greatest match in tennis history.  Nadal came into the match with a 23-match win streak while Federer had beaten Nadal in the previous two Wimbledon finals. 

Nadal and Federer ended up playing nearly five hours before Nadal finally won 9-7 in the fifth set amidst darkness since the match was already rain delayed. 

Now, Nadal and Federer can add another epic match to their rivalry with Nadal's sixth French Open win.  Nadal's four set victory 7-5, 7-6 (3), 5-7, 6-1 showed just how close these competitors are in skill level.

Their rivalry has certainly shown to be the best ever.  Each has been proclaimed by different analysts and experts to the best tennis player ever.  So which one is the best that tennis has ever seen?  On this day, Nadal showed he had the edge.