By Chris Oddo

(August 18, 2012) -- On the eve of  what promises to be another epic final between five-time Grand Slam champion Novak Djokovic and 17-time Grand Slam champion Roger Federer, we take a look inside the numbers of their most excellent rivalry.

20
Number of hard-court matches that the pair have contested. Federer leads 11-9, but has lost the last four (2011 US Open, 2011 Indian Wells, 2011 Dubai, 2011 Australian Open).

1
Number of times they have met in Cincinnati. Federer won the 2009 final 6-1, 7-5.

27
Number of matches they have played over the course of their brilliant careers. Federer leads 15-12.

11
Number of Grand Slam matches the pair has played. Federer took a 6-5 lead with his 6-3, 3-6, 6-4, 6-3 victory over Djokovic in the 2012 Wimbledon semifinal. No other pairing has met as often in Grand Slam play. Lendl-McEnroe have met ten times each in Grand Slam play. Nadal leads Federer 8-2 and Lendl was 7-3 versus Johnny Mac.

9
Number of Grand Slam semifinals that Federer and Djokovic have contested. It's the most all-time. The only two times that they've crossed paths at a Grand Slam match that wasn't a final was the 2007 US Open final and the 2007 Australian Open round of 16.

9
Number of players who have reached all four Grand Slam finals in the Open Era. Federer was the seventh to achieve the task (in 2006 at age 24), while Djokovic became the ninth at Roland Garros.

23-4
Record of player who wins the first set when Federer and Djokovic play.

4
Number of times that Djokovic has come back from a set down to defeat Federer ('09 Miami, '09 Rome, '10 US Open, '11 US Open). Federer has never rebounded from losing the first set against Djokovic.

10
Number of break points that Djokovic has successfully saved in Cincinnati this year, while not giving up a single break of serve. Federer has been perfect as well, saving all three break points he's faced.

1,168,128
Number of Twitter users that follow Novak Djokovic.

1,031,045
Number of Twitter followers that Djokovic had the day before he last played Federer at Wimbledon.

11,413,030
Number of Facebook users that currently "like" Roger Federer.

10,727,451
Number of Facebook users that "liked" Roger Federer's page before his last semifinal with Novak Djokovic.

12
Number of tiebreakers the pair have played. Each has won six, but Federer is 6-2 versus Djokovic in Grand Slam tiebreakers.

1
Number of times that Federer has told Djokovic's parents to be quiet.

11
Number of winner-take-all sets they have played. Djokovic has won 7 while Federer has won four.

(Photo Credit: Getty)