MELBOURNE, Australia — If anyone knows how Novak Djokovic feels after sweating and scrapping for almost five hours in an Australian Open semifinal, it's his next opponent, Rafael Nadal.A day after Nadal beat Roger Federer in four sets in their semifinal, Djokovic overcame Andy Murray 6-3, 3-6, 6-7 (4-7), 6-1, 7-5 on Friday in 4 hours, 50 minutes.Djokovic, the defending champion who is ranked No. 1 in the world, faces No. 2 Nadal for a third straight time in a Grand Slam final Sunday. Three years ago, Nadal had to regroup after a lengthy semifinal. He needed 5 hours, 14 minutes to get past Fernando Verdasco in the longest men's singles match in tournament history. He was so exhausted, he didn't lift a racket the next day.Yet in the final, he beat Federer, who had an extra day of rest, in five sets.Djokovic has less than 48 hours to prepare to face Nadal, one of the most fit players in the game."I know that I, maybe, have a mental edge because I had lots of success against him … in 2011," Djokovic said of Nadal. Djokovic won 10 titles in 2011, six by beating Nadal in finals. "That's going to be my main priority and concern the next day and a half, to physically be able to perform my best and be ready to play five sets," Djokovic said.Djokovic has shown chinks in his armor in this tournament. Against David Ferrer in the quarterfinals, he struggled to breathe through most of a straight-sets win and at one point clutched his leg in agony. Against Murray he looked spent when he hobbled gingerly back to his chair after dropping serve to go down 2-1 in the third set.Djokovic can win his fifth major title and become the fifth man in the Open era (since 1968) to win three consecutive Grand Slam titles. He also can make Nadal, a 10-time Grand Slam winner, the first man in the Open era to lose three consecutive major finals.After losing the past two Australian Open finals, Murray , though he went out a round earlier, left more encouraged than ever that he can break through and become the first British man to win a Grand Slam singles title since 1936."(Friday's) match was important for many reasons," he said. "Obviously I wanted to win, first and foremost. But also sort of after last year, the year that Novak's had, I think there's a very fine line between being No. 1 in the world and being 3 or 4. I think that gap, I feel (Friday) I closed it."Murray was annoyed after the match that drug testers wanted him to do urine and blood tests. "I've just done … the urine test," he said. "They just told me I need to sit down for 30 minutes before I can give blood. I want to get out of here. … On top of losing a match like that, it's really a frustrating thing to have to go through at 1 in the morning."At the 2009 U.S. Open, Murray complained when testers visited his hotel room at 7:15 a.m. on a day off to test him.