Rafael Nadal isn't convinced Novak Djokovic has any breathing problems going into their Australian Open final on Friday night.

During Djokovic's five-set semifinal win over Andy Murray on Friday, and to a lesser extent during his quarterfinal victory over David Ferrer, the Serbian player showed signs of breathing difficulties, something he's put down to allergies.

"He's done it many times before," Murray said. "He runs very well even when he's breathing heavy. I was ready for that. He was similar in the last match. But he moved fine."

Nadal said that he, like Murray, had seen it all before. Nadal suggested that Djokovic tends to make incredible physical recoveries, even in the latter stages of big matches.

"It's funny, no?," Nadal said. "I saw the match yesterday on the TV [...] when he was in the fifth set moving fantastically well, and they show images from 2 hours, 50 [minutes] before and seems like he was destroyed. Two hours 50 [minutes] later he was in perfect condition. So is difficult to imagine that he has these problems. I don't know."

For his part, Djokovic, who won three of the four majors last year, says the breathing issues are genuine in the southern summer conditions.

"I've seen doctor and I've talked with some people," Djokovic said. "I've talked with couple of players that have a little allergy problems this year in Australia for no reason, ones they didn't have in last couple years but they had reactions this year."