Miami, FL, USA, 1 April 2016 | AAP

Nick Kyrgios is the new king of Australian tennis after a breakthrough in Miami.

Kyrgios will crack the world’s top 20 and leapfrog Bernard Tomic to become Aussie No.1 on Monday after upsetting power-serving 12th seed Milos Raonic 6-4 7-6(4) to reach his maiden ATP Masters 1000 semifinal.

Three weeks shy of his 21st birthday, the volatile talent is the youngest man ever to make the last four in Miami and first Australian to do so since Lleyton Hewitt in 2002.

He next faces Japanese sixth seed Kei Nishikori for a likely shot at world No.1 Novak Djokovic in Monday’s (AEST) title match.

Raonic has been one of the hottest players on tour in 2016, downing Roger Federer to win the season-opening crown in Brisbane and racking up 17 wins from 20 matches.

But the Canadian was on the back foot from the outset after Kyrgios made a flying start by breaking Raonic in the opening game of the match.

“To be honest, I didn’t think I was going to break during the match,” Kyrgios said.

“I came out really energetic and got pretty lucky. That definitely made me more relaxed.

“I really learned how to return this year. That’s the major thing this year. I am giving myself so many more chances and getting so many more opportunities to take over matches.”

On Monday, Kyrgios is guaranteed to rise to at least 20th in the world and eclipse Tomic to become only the third player to hold Australia’s top ranking in the past seven years.

Tomic ended Sam Stosur’s unbroken six-and-a-half-year stint as the country’s highest-ranked player – man or woman – last September, but is projected to fall out of the top 20 next week after skipping Miami with a wrist injury.