A best-of-three format (say, Player A vs. Player B) can produce only four distinct three-set outcomes: ABA, ABB, BAA and BAB. A five-set match, on the other hand, has 12 possible set outcomes, creating a host of ways momentum can twist and turn over the course of several hours.

But it's not really about the numbers. In the latter stages of a five-set match, the stats give way to a clash of wills, a combination of skill, endurance and faith that pushes men to their physical limits and well beyond. The players are not merely competing anymore. They are suffering, fighting against joints that want to quit and lungs that feel ready to collapse. And because each player knows that the man on the other side of the net is suffering too, the struggle becomes mental as the players try to hide just how much pain they're in.

Champions are revealed in five-set matches, and pretenders are exposed. Doubt and fatigue are punished, while self-belief and stamina are rewarded. If there is one chink in Federer's legacy, it is his 2-3 record in five-set finals at Grand Slams, including two heartbreaking losses to Nadal.

Djokovic, meanwhile, has become larger than life in part because of his indomitable success in five-setters. Beginning with the 2010 U.S. Open, Djokovic is a staggering 8-1 in five-set matches at Grand Slams, including two wins over Federer, a win over Murray, and the unforgettable 2012 Aussie Open final victory over Nadal.

The Serb's implacable resolve was on display Monday when he refused to crumble against Stanislas Wawrinka in the fourth round in Australia. Down a set and two breaks, Djokovic rallied to take the lead and stood his ground when Wawrinka won a fourth-set tiebreak. After five hours and four minutes of grueling tennis, Djokovic finally prevailed 12-10 in the fifth set and once again celebrated by Hulking out of his shirt and bellowing in triumph.

Tuesday provided another five-set epic, with enough momentum swings to fill a whole tournament. Spanish pro Nicolas Almagro jumped out to a 6-4, 6-4, 5-4 lead over his countryman David Ferrer in the quarterfinals and was on the verge of winning his first match over Ferrer in 13 tries. But Ferrer broke Almagro and won the set, setting up a fourth set that beggared belief. Four times, Almagro broke Ferrer to take the lead in the set, and each time Ferrer broke back in the following game. Almagro served for the match at 5-4 and 6-5, but he couldn't even get a match point on his serve. When Ferrer won the fourth-set tiebreak to even the match, Almagro was a hobbled man, and he went down meekly in the final set.

Wednesday brought a third straight five-setter, this time between Federer and ebullient Frenchman Jo-Wilfried Tsonga, who famously came back from two sets down to beat Federer in the 2011 Wimbledon quarterfinals. After holding off Tsonga is five sets, Federer offered a fan-like perspective on the many five-set epics in his Grand Slam career.