Can Djokovic stay ahead of the pack?

Novak Djokovic says nothing's impossible as he sets out to repeat his jaw-dropping performances of last season, starting with the Australian Open grand slam from Monday.

The Serbian world number one won three of the four grand slams and five Masters titles in 2011, became the top-ranked player, put together a 70-6 winning record and banked a record 12.6 million dollars in prize money.

Last year's Australian Open final triumph over Andy Murray was the first of seven straight tournament wins in a 41-match winning streak that was finally ended by Roger Federer in the semi-finals of the French Open.

"My success gives me a reason to believe that I can win again. Why not?" Djokovic said.

"I think it doesn't make any sense to be anything other than optimistic. I need to believe in my qualities and my abilities and I need to believe that I can repeat the success.

"Of course it is going to be an incredibly difficult task to achieve, but you never know, nothing is really impossible."

Djokovic, 24, dominated men's tennis last year, winning a career-best 10 titles in 11 finals. He defeated world number two Rafael Nadal six times and overall was 21-4 against top-10 opponents.

But his incredible season now marks him as the hunted as his top rivals Nadal, Federer and Murray will be out to prevent Djokovic from sweeping all before him again.

"What he (Djokovic) did, (is) very difficult for him to do again," former US Open champion and world number 11 Juan Martin del Potro said this week.

"I think Roger and Rafa (Nadal) will be going after Novak because they don't want him to repeat the year he just had."

Djokovic's landmark season took its toll with a combination of back and shoulder trouble, but the Serb said he was now injury-free.

"Injuries are past at this moment," he said. "I am happy to announce that it has been a couple of weeks since my last match and I have had enough time to recover physically and mentally and to get back into shape."
But Nadal finished last season with a sore left shoulder and was not sure whether he would be at his peak during the Australian Open.

"I know I am working well, with a much more positive attitude than I had during the second half of last season, especially in the final stretch," he told Catalan sports daily Sport.

"I see myself capable of having a good tournament but you never know. I am happy with the level of my game, of how I am doing things and I think I am sowing seeds that will bear fruit. But maybe not in Australia."

Ten-time grand slam champion Nadal, 25, has a chequered record at the Australian Open, winning in 2009 but failing to make the semi-finals in three of the last five visits.

World number three Federer withdrew from last week's Qatar Open with back spasms but is confident of playing in Melbourne to continue his remarkable record at the major tournaments.

All-time grand slam champion Federer, 30, has played in 48 consecutive slams and won the Australian Open four times, but was beaten in straight sets by

Djokovic in last year's Melbourne semi-final.

"Although it's not very good it's not crazy-bad," Federer said of his injury. "I have had bad backs on the past, but this is not very good.

"I feel that without play and with the right treatment, I will get through it."

World number four Andy Murray, 24, bidding to become Britain's first male major-winner since Fred Perry in 1936, has suffered shattering defeats to Federer and Djokovic in the last two Australian Open finals.

He now has tennis great Ivan Lendl as his coach and got an immediate return with a crushing win over Ukraine's Alexandr Dolgopolov in the final of the Brisbane International last weekend.

Murray will be in the mix again in Melbourne, and will hope to show has the mettle to break his 0-3 record in grand slam finals.

"A year wiser, and have a year's more experience," he said. "I think I've improved a few things in my game."