The anticipation of final Sunday

Thirty-nine times Novak Djokovic and Rafael Nadal have played and there is nary a discernible difference between the two. The favorite usually depends on which player lost his last encounter, giving motivational edge to the other.

Djokovic has won 10 of their past 16 meetings. Nadal has won six of their past nine. Djokovic has won two in a row. Djokovic snapped Nadal's eight-year championship hold on the Masters 1000 event at Monte Carlo last year. Nadal beat Djokovic in both Grand Slam confrontations in 2013, first at Roland Garros to deny Djokovic a chance at the career Grand Slam for the second consecutive year, and then in the US Open final. Nadal ripped through the calendar and enters 2014 as the top-ranked player in the world, wresting the title from, naturally, Djokovic.

They orbit one another anxiously and deliciously. The absence of one or another from the tour of a tournament creates opportunity for other players (David Ferrer rose to third in the world; Andy Murray won the US Open in 2012 without having to deal with Nadal for once), and a void in the anticipation of championship Sunday.

Nadal hasn't played the Australian Open since losing their epic 5-hour, 53-minute final in 2012, and while a rematch in the final would be the ultimate theater to start 2014, a healthy Nadal-Djokovic rivalry for a full calendar year would carry the sport into a place last seen when Roger Federer and Nadal were playing for titles.

Each strives for individual goals while simultaneously keeping an eye on the other. Djokovic, with six Grand Slam titles -- four of them in Australian -- seeks the career Grand Slam. A Nadal win in Melbourne would give him at least two titles in each Slam event, tie him with Pete Sampras with 14 and give him an even better chance to catch Federer's record of 17 major titles.

The wonderful byproduct of their rivalry is how Djokovic and Nadal have affected the mechanics of the other's game. It was the immutable Nadal toughness that both forced Djokovic to fight harder on the tennis court and allowed him to beat Djokovic twice at Grand Slam events last year -- especially down a break in the fifth set in their epic semifinal at Roland Garros. There is Djokovic's court control, which leaves Nadal more vulnerable against him than any other opponent in the game -- forcing Nadal to improve his groundstrokes on hard courts, especially. There is Djokovic's improved serve. According to Greg Sharko at the ATP, Djokovic is now holding 88 percent of his games (tied with Nadal) and winning a staggering 60 percent of his second-serve points. He is already ranked second in return games won.

Nadal is first on the tour in return games won. Djokovic is second.

Djokovic can exploit Nadal's short backhand reply by stepping in, which helps the Serb gain court position. Nadal may beat Djokovic, but at numerous times over the past two years, Djokovic had the game to overpower Nadal in ways that force the Spaniard to start fast, to win the first set or risk perishing quickly, as he did in straight sets in both the Beijing and year-end championship finals.

Djokovic is 15-2 against Nadal when winning the first set. Nadal hasn't beaten Djokovic after losing the first set since their epic 3-6, 7-6 (5), 7-6 (9) Madrid semifinal in May 2009.

After Nadal lost seven straight finals to Djokovic between 2011 and 2012, Nadal was forced to completely retool major portions of his game. He needed more free points from his serve. He could escape against other players, Federer included, with less depth on his groundstrokes, compensating with spin and placement. But short replies cost him dearly against Djokovic, who has been untroubled by the height of Nadal's ball to his backhand, able to redirect a ball that vexes the rest of the tour down the line for a winner.

Djokovic's loss to Nadal in the 2010 US Open final was the first springboard (Serbia's Davis Cup win was the other) to his rededication to and refocusing on his game. It was Nadal who best exposed Djokovic's lack of belief during the most crucial times. Djokovic learned he could not rely on the weapons he would need to become a transcendent player. But that all changed. The result was a 70-6 2011 with three majors for the Serb.

After his losses, Nadal readjusted following the 2012 final in Melbourne, and the result has been a mesmerizing test of wills between the two players. Nadal has beaten Djokovic with a champion's combination of adjustment and determination. Nadal's backhand, curiously short and vulnerable traditionally, has become a weapon for Nadal, who now steps in and uses it frequently as a finishing shot. Nadal, one of the game's best volleyers, now comes to the net often, providing variation and a willingness to attack and end points. These adjustments have virtually all come in response to the Djokovic onslaught. Each has made the other better, more formidable, more dangerous.

Although Nadal attacks the court with more aggression and play inside the baseline, he has also forced Djokovic -- the man of the iron will -- to blink. Djokovic double-faulted on match point to give Nadal the title in the French Open final in 2012 and oddly lost his composure at Roland Garros last year, complaining about the grounds crew and its timing in watering (or not watering) the clay. It was a psychological slip that unraveled Djokovic and toughened up Nadal.

After it appeared Djokovic had begun to control the match in the 2013 US Open final, Nadal grounded Djokovic into wild mistakes from which he could not recover, losing 6-1 in the fourth and final set.

The Australian Open is the beginning for these two, but not the end. Nadal and Djokovic play their matches with a kind of Promethean importance, similar to the Nadal-Federer matches of old. They play with the knowledge that they are the two best players in the world, and their intensity carries the rest of the sport.