Rafael Nadal's build up to next week's Australian Open hit a hurdle on Tuesday when a leg injury forced him to pull out of the last major warm-up tournament.

The Spanish world number two was trailing Australian wildcard Chris Guccione 6-5 in the opening set of their first round clash at the Sydney International when he decided he had had enough.

Nadal had felt pain in his right inner thigh and said he didn't want to risk doing any more damage with the first Grand Slam of 2007 less than a week away.

"I was trying on court, but I did not feel 100 per cent," he said.

"The trainer came onto the court and I asked him... and he said to me if I continued then it could get worse, so I stopped."

Nadal was forced to miss last year's Australian Open with a foot injury but said he had no doubts he would be able to play in Melbourne this year.

"I'm going to play for sure. There's nothing broke," he said.

"I hope in two more days I will be 100 percent because I want to play the Australian Open for sure.

"It's very important for me, and last year I couldn't play, and this year I want to play there, it's important, so I will try my best."

Nadal said he had never experienced any problems with his thigh before but began to notice there was a problem when he flew from Chennai to Sydney at the weekend.

The 20-year-old left-hander said he would have to rest for the while he continues to get treatment on the injury for the next few days and would undertake a course of anti-inflammatories to reduce the swelling.

"The physio said if you continue, that's going to be worse," Nadal said.

"They tell me it's very tired, and they feel with treatment, in two more days, going to be 100 per cent."