A look at the numbers ahead of Djokovic and Nadal's clash at Wimbledon

It’s not just one of the deepest rivalries among active players, it’s one of the deepest rivalries in the Open Era. And on Friday afternoon, Rafael Nadal and Novak Djokovic will walk onto Centre Court and battle it out for a spot in the Wimbledon final—the 52nd match of their head-to-head series.

Both players were tested in their quarterfinals on Wednesday—first Djokovic was pushed to four sets by Kei Nishikori, 6-3, 3-6, 6-2, 6-2, then Nadal was pushed to the absolute limit to make it past Juan Martin del Potro, surviving the Argentine after four hours and 47 minutes, 7-5, 6-7 (7), 4-6, 6-4, 6-4.

Those victories propelled Nadal and Djokovic into an absolute blockbuster semifinal clash. It will be their 14th career meeting at a Grand Slam, the second-most meetings between two men at a Grand Slam in the Open Era (Djokovic and Roger Federer have played 15 times at Grand Slams).

WATCH—Daily Serve from Day 9 at Wimbledon:

Nadal leads Djokovic in their first 13 Grand Slam meetings, 9-4, but broken down it’s far more even:

~ They’ve split their last eight Grand Slam meetings, 4-4 (Nadal won the first five).

~ Away from Roland Garros, they’re at 3-3 (Nadal’s won six of their seven French Open meetings).

~ At Wimbledon, they’re 1-1 (Nadal won in the 2007 semifinals and Djokovic won in the 2011 final).

“We always played in important stages, important places,” Nadal said of the rivalry. “Friday will be another important match against an opponent that is one of the most difficult ones that you can face.

“And I saw matches of him, he’s playing well—the only way to try to win it is to play very well.”

Overall, including tour-level meetings, Djokovic just edges Nadal in their head-to-head history, 26-25.

Here are a few more things to think about on Friday:

~ Nadal actually leads Djokovic on grass, 2-1 (they’re 1-1 at Wimbledon but Nadal won their only other grass-court meeting in the final of Queen’s Club in 2008, 7-6 [6], 7-5)

~ Djokovic has 12 career wins over No. 1s (that includes two wins over No. 1s at Grand Slams—Federer in the 2008 Australian Open semifinals and Nadal in the 2011 Wimbledon final).

~ Nadal hasn’t lost a Grand Slam semifinal in almost nine years (the last time the Spaniard lost in a Grand Slam semifinal was at the 2009 US Open to del Potro—who went on to win the title).

Strokes of Genius is a world-class documentary capturing the historic 13-year rivalry between tennis icons Roger Federer and Rafael Nadal. It is timed for release as the anticipation crests with Roger as returning champion, 10 years after their famed 2008 Wimbledon championship – an epic match so close and so reflective of their competitive balance that, in the end, the true winner was the sport itself.

WATCH: NOW AVAILABLE AT THE ITUNES STORE