Rafa Nadal believes his quest for a fourth consecutive grand slam is mission almost impossible and the world number one belted back Roger Federer's suggestion the flu-hit Spaniard is the Australian Open favorite.

Nadal holds the French, Wimbledon and U.S. Open crowns and will bid to become the first man since Australia's Rod Laver in 1969 to hold all four majors concurrently.
The Spanish world number one has already said the feat has no bearing on his preparations and was similarly dismissive when pressed by reporters to talk about his chances.
I think (it) is almost impossible, said Nadal when asked about Laver's record. It's very, very difficult. Tennis is a very competitive sport and (there) is not a lot of difference between players.

So a lot of matches are decided in a few balls. So for that reason it is very difficult to have one player winning everything.

I think it's better if we continue with other questions because for me, seriously, I can't answer this question because I (cannot) imagine (it).

I think if that does happen, for sure, I am gonna be more happy to win in Australia because it's the Australian Open more than because it's the fourth in a row. That's 100 percent true.

Nadal retired with knee problems in the quarter-finals last year when trailing Briton Andy Murray by two sets, and has been under another fitness cloud in the lead-up to Australia due to a stubborn flu that dogged him throughout the Qatar Open.

The Spaniard was frank about his condition two days before the tournament starts Monday.

I'm feeling better. I think not perfect yet, he said.

But seems like after what I had in Doha, when I (am) practicing, I feel a little bit more tired than usual and sweating more than ever.

But the truth is I'm better than few days ago. So that's very positive.

Nadal's arch-rival and defending champion Roger Federer had earlier anointed the Mallorcan favorite to win his 10th grand slam but he was quick to belt the compliment straight back into Federer's court.

No. For sure no, said Nadal, who holds a 14-8 record over the Swiss maestro. Every tournament is completely different. But I feel if I play at my best level, I can have a chance to be in the second week, and there we will see what happens.

But for sure (I) am feeling less favorite than (Federer) and not more favorite than (Novak) Djokovic, Murray, (Robin) Soderling, these kind of players.

The Nadal-Federer rivalry has lit up the men's tour for years and the pair have taken all but two of the last 20 grand slams, but the Spaniard said their duopoly was set to be broken.

I think that's impossible to continue like this. But there is a lot of good players, a lot of young players, and every year is more and more difficult.

At 24, Nadal has more time than 29-year-old, 16-times grand slam winner Federer to add to his major tally, but suggested that motivation to keep a step ahead of the pack was a quality both shared in abundance.

I think the important thing is keeping focus, keeping have the right ... motivation to improve your tennis even if you are on the top, he said. And I think that's why Roger is on the top for a long, long time.

I am a better player than three or four years ago. So that's something that is important personal satisfaction.

That's why I am practicing every day.