MELBOURNE, Australia — Novak Djokovic’s remarkable 2011 season included a 43-match winning streak, three Grand Slam tournament victories, 10 titles overall and a 70-6 record. But the most mind-boggling number of all was this: The Serb went 6-0 against Rafael Nadal, all in finals and twice in majors.

That Djokovic flipped the script so suddenly against the fiercest competitor in tennis was the story of the year. Djokovic had never defeated Nadal in a final before last year and no one foresaw his turning the tables so quickly and decisively, especially considering that Nadal had won three Grand Slam titles in 2010 and prevailed in both meetings with Djokovic. But Djokovic handled the Spaniard in the biggest tournaments, on three different surfaces, including twice on Nadal’s beloved red clay. When Djokovic beat him for a sixth consecutive time, in the U.S. Open final in September, Nadal looked broken both in spirit and body, bending over with his hands on his knees, the athlete’s signal for a tap-out.

Nadal, a 10-time Grand Slam champion, hasn’t spent much time as anyone’s punching bag in his career, and he vowed after the U.S. Open to “accept the challenge and work” to halt Djokovic’s dominance. Nadal’s first opportunity to do just that comes Sunday, when the top two players in the world meet in the Australian Open final (3;30 a.m., ESPN2), their Open Era-record third consecutive clash in a major-championship match….