Known as "The Reaper", a steely-faced Whittaker allowed himself a smile as the 1000-strong crowd that had gathered to watch the press conference broke into an Aussie chant on Friday.

The middleweight mixed martial arts champion hoped he would have similar support in his first title defence in Australia, at Rod Laver Arena.

"I'm going to be in there giving it everything I've got anyway," Whittaker said.

"Normally you can block the crowd out but the Rod Laver Arena is something special, it's really crazy."

Selling out in just eight minutes, the UFC 234 card includes UFC legend, Brazilian Anderson Silva, up against trash-talking rising Kiwi star Israel Adesanya.

UFC boss Dana White confirmed the significance of their fight on Friday, saying the winner would become the No.1 contender in the middleweight division.

Silva, 43, had the longest title reign in UFC history at more than six years.

Whittaker (20-4) is on a nine-fight winning streak and hasn't lost in five years although is on the comeback after breaking his hand in his epic showdown with Yoel Romero last June.

The American (15-3 plus one no contest) predicted the fight would finish in a first round knock-out.

"He might - a lot of people have said that," Whittaker said.

"He's got a good punch on him but I hit pretty hard myself.

"He's going to be a true test of my character and abilities."

Gastelum, 27, rose to fame when he won the television show The Ultimate Fighter back in 2013.

Previously working as a bail bondsman, walking into the Octagon holds no fear.

"Nothing in my life has ever been given to me, everything I've worked for I've had to take and here I am in Australia I'm going to take that gold," Gastelum said.

Australian Associated Press