Novak Djokovic tamed Milos Raonic's formidable serve before humbling the Canadian 7-6, 6-4, 6-2 at the Australian Open this morning to set up a mouth-watering semi-final against defending champion Stan Wawrinka.

Eighth seed Raonic, who pushed deep at the grand slams last year, was supposed to offer the first real test for the top-seeded Serb, but was completely outclassed under the lights at Rod Laver Arena.

After being edged in the tie-break, Djokovic broke Raonic early in the second set and twice in the third, without giving up a single break point on his own serve.

He closed out the two-hour match with a clinical volley and will play the man that ended his title defence at Melbourne Park in last year's quarter-finals.

Wawrinka defeated fifth seed Nishikori 6-3, 6-4, 7-6 in two hours and four minutes on Rod Laver Arena and has dropped just one set in reaching the last four.

Nishikori had won their previous encounter, also in the quarter-finals of a grand slam, in five sets on his way to the final of the US Open at Flushing Meadows last year.

But fourth seed Wawrinka dominated today's match from the outset and his only nervous moments came when Nishikori saved five match points from 6-1 down in the tie-break.

"I am still nervous at the end of the tie-break," admitted Wawrinka, who eventually took his sixth match point with his 20th ace. "It's never easy. He is returning well and you have to go for it. I was a little bit defensive, but I am happy to get through."

Asked about his approach to the tournament, Wawrinka added: "I don't come back to defend, I don't come back to win again. I come back to start a new grand slam

"There is no easy match (in the semi-final), it's going to be a tough one against Novak, but so far I am playing well and am so happy to be back and playing the semi-final again."

Nishikori admitted he paid for a slow start and could regret an audacious attempted drop shot which gave Wawrinka his sixth match point.

"I started to feel more comfortable in the third set, especially after I found out that I could go a little more aggressive than the first and second set," the 25-year-old said.

"I was mixing up serve and volleys. My serve was much better than first couple sets because I was making more first serves. I was struggling with my serve and that's why I couldn't get a good rhythm in the first and second set.

"The tie-breaker was really close. If I could get that one, it might change the whole thing. But, you know, he was serving really well until end of the set.

"So I think I have to give him credit. He obviously played really aggressively and played great tennis."