Now Becker's influence is there for all to see as Djokovic eyes revenge on Friday night in the third instalment of his compelling Melbourne Park rivalry with Wawrinka.

Djokovic's epic five-set loss to the Swiss 12 months ago not only ended the Serb's three-year reign in Melbourne but also his remarkable run of 14 successive grand slam semi-final appearances.

It also came just weeks after Djokovic appointed Becker as coach, a move that raised eyebrows in tennis circles despite it continuing the growing trend of today's stars turning to yesterday's heroes to gain a grand slam edge.

Now, though, tennis's odd couple are flying, Djokovic passing Becker on the all-time major leaderboard with his second Wimbledon crown last year and returning to world No 1 with the German great in his corner.

But until Djokovic's near-flawless charge to the Australian Open semi-finals, specific evidence of Becker's input had been hard to gauge.

Not so anymore, with the Serb's serving under Boom Boom's tutelage imperious at Melbourne Park, as close to perfection as the top seed can ever recall.

Djokovic has won 73 of 74 of his service games, a 99 per cent strike rate that only adds to his supreme confidence there will be no repeat of his 2014 mugging by Wawrinka.

The four-time champion acknowledged Becker's input as key in delivering a stress-free run to the last four.

"Definitely he's got his contribution there, no question about it," Djokovic said after his straight-sets quarter-final dismantling of Milos Raonic.

"He joined the team last year. It's been 12 months that we've been working together.

"He's working closely with Marian [Vajda] and the rest of the team members obviously in improving my game, getting it to the highest possible degree.

"Serve was one of the tasks, one of the things that we wanted to improve.

"I know I can't serve as fast as Milos, but I'm trying to use the angles, the accuracy, align myself to have some free points with that serve."

Djokovic will again rely on his improved delivery against Wawrinka, the only player to have beaten the Serb at Melbourne Park in five years.

In addition to last year's classic, the two engaged in a gripping five-setter in 2013 which Djokovic won, before Wawrinka turned the tables en route to claiming his maiden grand slam title in 2014.

"I'm ready for the battle," Djokovic said, noting how Wawrinka must be too after his three-set quarter-final win over Kei Nishikori.

"He played a great match. Kei has been playing his best tennis in the last 12 months. To be able to win straight sets against him is pretty impressive. Being the defending champion, obviously he's got some of the pressure here.

"He is facing this kind of role for the first time in his life." AAP