Sydney NSW, Australia, 13 January 2015 | AAP

World No.1 Novak Djokovic says young Aussies Nick Kyrgios and Thanasi Kokkinakis will prove stiff competition for his fourth Australian Open title bid in five years.

The seven-time grand slam champion said the teenagers will be tough to dislodge on home soil.

“Nick and Thanasi, they’re very talented players,” he said.

“I fancy my chances, but… I’m sure with the crowd support they’ll be very tough opponents.”

The four-time Australian Open winner has been in stunning form except for a shock loss to Croatian Ivo Karlovic in Qatar last week.

Djokovic said with increased maturity, 19-year-old Kyrgios was tightening his game.

“Nick had the quarter finals at Wimbledon last year, beating Nadal on the way, so you’ve got to give him credit for that,” he told Fox Sports.

“He’s still very young but he’s showing some power on the court.”

The teenage ace gets his Sydney International campaign underway on Tuesday night, opening his 2015 season against world No.42 Jerzy Janowicz.

A towering figure at 203cm, Janowicz is a Wimbledon semi-finalist and will pose a tough challenge for Kyrgios.

The Canberran is looking to shake off a back injury which kept him out of the Hopman Cup and will be returning for his first ATP event in three months.