Australian enigma Nick Kyrgios has again used his unusual tactics and pure tennis craft to power into the Miami Open of 16 on Monday.

The Australian world No.33 was far too strong for his lower-ranked opponent, slamming 12 aces and winning 81 per cent of first-serve points to thump Serbian Dusan Lajovic 6-3 6-1.

He produced two underarm serves, including an ace, among several trick shots.

Quickly becoming his trademark…@NickKyrgios with the underarm ace 😂 pic.twitter.com/W5JbbE8n8V

— Tennis TV (@TennisTV) March 25, 2019

But the often controversial 23-year-old also found himself in a mid-match verbal altercation with a spectator before the man was ejected from the venue.

“I had a bit of fun with it. I knew that I was going to get him kicked out,” Kyrgios said.

“I loved it, I loved every single bit of it. I think the crowd loved it.”

Kyrgios will next meet Borna Coric for a place in the quarter-finals after the Croatian overcame Frenchman Jeremy Chardy.

“I don’t know what tomorrow is going to bring on the tennis court, but I’m going out there and having fun,” Kyrgios said.

“I served well and returned well and I’m really happy.

“Today it was a pretty good all-around performance.”

Ever seen this before?!@NickKyrgios salutes the ball before he converts the smash 😂#MiamiOpen pic.twitter.com/98FnTDhSwU

— Tennis TV (@TennisTV) March 25, 2019

Kyrgios has a strong record at the Miami Open, reaching the fourth round for a fourth straight year.

He was a semi-finalist in 2016 and 2017, and reached the Round of 16 last year before falling to Alexander Zverev.

Earlier, world No.1 Novak Djokovic was stretched to three sets but powered through the decider against Federico Delbonis.

Djokovic, aiming for a seventh title in the Masters 1000 event, overcame a second-set hiccup to prevail 7-5 4-6 6-1.

“We were very close in the beginning of the third set … It could have gone a different way,” Djokovic said.

Next up for Djokovic will be Spanish 22nd seed Roberto Bautista Agut, who prevailed 6-4 6-4 over Italian 15th seed Fabio Fognini.

Defending champion John Isner was broken in the first game but he held the rest of the way and served 16 aces to beat Albert Ramos-Vinolas 7-5 7-6 (8-6).

Isner, now 33, won the biggest title of his career in the tournament a year ago.

The American seventh seed will face Kyle Edmund who defeated 12th seed Milos Raonic 6-4 6-4.

Others to progress to the last 16 on Sunday were 17th-seeded Georgian Nikoloz Basilashvili and 18-year-old Canadian qualifier Felix Auger Aliassime.