TENNIS:WORLD NUMBER three Novak Djokovic believes Roger Federer and Rafa Nadal's stranglehold on men's tennis is slowly loosening.

The Serb said yesterday the rise in genuine contenders capable of breaking the grand slam dominance of Federer and Nadal has given a boost to the sport.

“I think it’s getting very interesting, men’s tennis,” Djokovic said at Melbourne Park on the eve of the year’s first slam at the Australian Open.

“It’s good for the sport to have a good group of the players able to win a major event or a grand slam,” added Djokovic, one of only two players other than Federer and Nadal to win a grand slam title in the past 19 majors when he won the 2008 Australian Open.

“The last five, six years the dominance was obvious from Federer, Nadal. They’ve been winning all the grand slams they’ve played. But now in last two years or so the things are changing a little bit . . . we have more belief that we can win a grand slam.”

Djokovic, Britain’s Andy Murray, Argentine Juan Martin del Potro, who won the US Open last year, American Andy Roddick and Russia’s Nikolay Davydenko all present threats to the Swiss number one and Spanish number two.

The Serb played at the invitational Kooyong Classic as his only warm-up ahead of his Australian Open first round match and has deliberately adopted a more low-key approach to remain fresh.

“Considering the amount of the matches I played last year, I tried not to commit to any events and just practice and be fresh for the Australian Open, which is the most important tournament,” he said.

“I just wanted to get some practice matches under my belt before I come to Melbourne Park. I was focusing on some other things and working hard off court.”

Djokovic, who blasted away from the baseline to win the 2008 Australian Open title, also said he had been working on giving his game greater variety.

“I think I improved on my net play and my physical ability, (and) strength. I’ve put some variety in the game, some volleys and serve, I’ve changed some things,” he said.

“I might not play as well as I did in 2008 from the baseline, but I still have a lot of belief that I have a great game.

“I know it’s a process and it cannot happen overnight and I cannot learn all the things as soon as I try to practice them.

“So I’m going slowly. I’m taking things step by step.”