Serb Novak Djokovic will enter the Australian Open semi-finals in peak mental and physical health as he looks to break Roger Federer's grip on the year's first Grand Slam.

Djokovic will meet the Swiss champion, who has won three of the past four Australian Opens, providing Federer gets past American James Blake in Wednesday night's quarter-final.

The No.3 seed booked his passage to the last four with a relatively smooth 6-0 6-3 6-4 quarter-final win over Spain's David Ferrer.

"I'm feeling really, really good at the moment both physically and mentally," Djokovic said after dumping Ferrer in straight sets.

"I'm showing all my strength and I've made some changes."

"I was working on my skills in the past couple weeks and I changed my strings and I'm feeling really good now."

"I'm playing with a lot of confidence. It's always good to start the year with such a great success."

"Playing a semi-final in a Grand Slam has become my routine in the last year or so."

"I'm always trying to push myself on the most important events to play my best tennis, which I did, and it's a positive thing for the future."

Djokovic looked a man in a hurry as he closed out the first set against Ferrer in just 23 minutes.

The second set also went to script before the 20-year-old found himself in a dogfight for the third, eventually winning 6-4 after warding off several break points.

"I'm very happy with my performance today, even though I was struggling a little bit in the end," Djokovic said.

"I knew that I would have to play basically every point with hundred percent focus because David is the kind of player who runs all the time and tries to get in the match and physically is one of the fittest players in ATP Tour."

"I was aware of that fact and that's why I was quite nervous in the end. But I managed to hold on."

Ferrer was left to lament a slow start from which he never fully recovered.

"I started very badly, very nervous and it was a problem in the first set," he admitted.

"He was playing better than me and with more confidence."

"In the important moments he served well."

"For me it wasn't a good day. I made too much mistakes and I lost a little bit of focus."

"Novak is a very good player and if I'm not well mentally it's impossible to beat him."

www.australianopen.com/en_AU/news/articles/2008-01-23/200801231201077228484.html