The two best men's players in the world—the Australian Open champion against the Wimbledon champion—with their season series tied at two matches each, doing battle in the final match of the 2012 season.
Djokovic bested Federer in Rome and at Roland Garros, while Federer was the victor at Wimbledon and in Cincinnati.
Monday's final will mark the 29th time that the two have met, with Federer holding a 16-12 advantage.
Neither man had an easy path to the finale, with Djokovic needing three sets to dispatch Juan Martin del Potro 4-6, 6-3, 6-2, while Federer bested U.S. Open champion Andy Murray 7-6 (5), 6-2.
Federer has won the ATP Finals six times before, including each of the past two years, while Djokovic has only the 2008 title on his resume.
Playing as often as they have doesn't give either man the advantage; instead, it evens the playing field, with each knowing the other's strengths, weaknesses and tendencies.
It's only fitting that Djokovic and Federer will contest the final match of the season, seeing as how the two of them, along with the aforementioned Murray, have basically had their run of the sport since Rafael Nadal went down with an injury in June and did not return to action.
I like Federer in this one, simply because of his string of success at the event. It wouldn't be shocking in the least to see Djokovic walk out of the O2 Arena in London victorious.
The showdown will air on ESPN 2 at 3:00 p.m. ET, and make sure to check with B/R for the latest news and analysis leading up to the match.