Japanese star and world No.5 Kei Nishikori has forecast a generational change this year at the top of world tennis, which has been ruled for the past decade by the big four of Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray.

Emerging Croatian teen Borna Coric, 18, and ranked 95 in the world, has also compared his game this week to world No.1 Djokovic and Murray, pronouncing himself the "best of my generation".

Kyrgios, 19, has been touted by many experts as a future grand slam contender, the former world junior No.1 now Australia's top ranked player at 50 and carrying the hopes of the host national at this month's Australian Open.

While he famously beat then-world No.1 Nadal on his way to the Wimbledon quarter-finals last year and was invited to train for a week with Federer, Kyrgios said the younger generation – himself included – still had a lot of work to do to reach their status.

Before last year, Federer, Nadal, Djokovic and Murray had shared 37 of the previous 40 grand slam titles.

Last year was the worst return in majors for the big four in a decade, Swiss Stanislas Wawrinka winning the Australian Open and Croatian Marin Cilic the US Open. Canadian Milos Raonic, 24, and Belgian Grigor Dimitrov, 23, are also among the young guns aiming at tennis supremacy.

But Kyrgios, confident in his ability, was also cautious to predict an overthrow of the big four.

"I read Coric made a statement that he was the best player of his generation and he plays like Djokovic. I sort of giggled to myself a little bit," Kyrgios said.

"He's had a couple of good results and he's already thinking that he's playing like Djokovic or Murray. You can always get into a bit of trouble thinking that sort of stuff, because those by far have so much more strength than us physically and mentally. We've got a lot of work to do, the young guys.

"The big four are still there, they're still definitely the hardest guys to beat. I think that's going to continue for the next two to three years. People talk about the changing of the guard, but those guys are consistently making finals and winning tournaments, I think guys like Dimitrov, Raonic as well.

"I'm not sure if we're seeing a changing of the guard just yet. There's a lot of young guys coming up but it's not just about having a couple of good results here and there, it's about staying consistent and challenging these guys on a daily basis."

Despite playing in just his second Australian Open, Kyrgios carries an enormous weight of expectation and the unseeded teen is a $34 eighth favourite.

But Kyrgios has played down immediate pressure, claiming his aim is sustained success.

"That's what I'm aiming for, to stay consistent and be at the top for a long time," said Kyrgios, who makes his comeback from a back injury at the Sydney International.

"Roger [Federer] has been the best for 10 years-plus; you model yourself around a guy like that, that's ideal.

"I trained with Roger for a week in Zurich. That was a really good experience, one of the most fun things I've ever done. It was unbelievable that he was always wanting to get better when he was on the court, he was creating drills for himself that I'd never seen before. He was always striving to get better and I think that's why he continues to stay at the top."