Novak Djokovic needs no extra motivation as he aims to win the Australian Open for a 10th time, as his confidence levels continue to rise.

Djokovic stormed into the semi-finals with a 6-1 6-2 6-4 thrashing of Andrey Rublev on Wednesday.

The Serbian has never lost a semi-final in Melbourne, while he has matched Andre Agassi for the longest Australian Open win streak in the Open Era (26).

Asked if this is as confident he has ever felt at the season's opening major, the 21-time grand slam champion told reporters: "I can't really say that this is as confident that I ever felt because I've had some incredible seasons, years here in Australian Open, some matches that are really unforgettable for me.

"I've been fortunate to really live through a lot of success in Australian Open. But [in the] last two matches, playing against two guys that are really good players, in-form players, to beat them dominantly in three sets is something that sends a message to all my opponents remaining in the draw.

"With this kind of game, of course the confidence level rises. I feel good on the court, better and better as the tournament progresses.

"I've been in this situation so many times in my life, in my career, never lost a semi-final at the Australian Open. Hopefully, that will stay the same."

When it was put to Djokovic that he is even more motivated at the age of 35, Djokovic said: "I don't think that I lack determination.

"I always try to give my best, particularly in grand slams, because at this stage of my career those are the tournaments that count the most, of course.

"You could say that there is something extra this year. You could say because [of] the injury, [and] what happened last year. I just wanted to really do well.

"I have a perfect score in Australian hard courts, in Adelaide and here. I've been playing better and better. I couldn't ask for a better situation to be in at the moment."

Djokovic will face Tommy Paul in the last four, after the American defeated compatriot Ben Shelton.

Paul has never faced Djokovic, who nevertheless knows what to expect.

"I know how he plays. I never faced him on the court, but he's been around for a few years," said Djokovic.

"I watched him play quite a bit, especially during this tournament. He's been playing probably tennis of his life. Very explosive, very dynamic player.

"I think he can hit all the spots with the serve. A very complete player. First semi-final for him, so of course he doesn't have much to lose."

Three American men progressed to the quarter-finals in Melbourne for the first time since 2000, and the first time in any grand slam since 2005, and Djokovic believes a strong United States contingent is crucial.

"America for our sport is an extremely important country," Djokovic said. "We have some of the biggest tournaments in the world played there.

"I think it is important that we see successful American men and women. Now you have a list of maybe four or five young players that are knocking on the door of the top level. I think that's great for our sport."