Rafael Nadal revealed he had remodelled his serve as he prepares for the Australian Open.

The 17-time grand slam champion confirmed on Saturday he had made changes to his serve ahead of the year's first major.

Nadal, 32, said his desire for a fresh challenge led to the move, with the serve to be put to the test competitively for the first time when the Spaniard faces James Duckworth on Monday.

"You need to make you feel alive, you know. There is always things to improve. It's true that I try to improve during all my career all the things," he told a news conference.

"The serve was always a thing that I tried to improve, and I think I did. Maybe it was the time to try to make one more step, no? That's what we are trying.

"I'm happy with it. I'm happy with the motivation to do something new. I'm happy with the fact that, if I am able to make that happen in a good way, that hopefully will give me the chance to help me on my game longer term. That's all.

"I didn't compete with this new serve, so let's see how it works. I am confident it's going to work well."

Nadal goes into the Australian Open having withdrawn from the Brisbane International due to a thigh strain, while he underwent ankle surgery in November.

But the 2009 champion in Melbourne played down any concerns over his fitness, saying: "I feel good.

"If I am not feeling good, I will not be here. I have good feelings in terms of the surgery that I have in the foot. I can say it's almost done.

"Then, of course, after surgery, after months without competing, having troubles to practice, of course there is always issues when you come back. But nothing new for me.

"Just accept the challenges the body presents and the tennis presents. It's again another season, coming back from a tough period of time, but with highest motivation possible to start another season.

"I'm very excited to be back here in Melbourne, starting another one."