"When I got my first car – that was it. I had made it. The next one was: let's just try and get a place of my own so I can be independent.

"I've come so far from that point, I would never have believed myself."

Loading

And what would Whittaker's reaction have been if someone told him when he was still fighting in Australia's Cage Fighting Championships that he would one day sell out Rod Laver Arena in eight minutes? "Bullshit."

But that is the reality for Whittaker and he was certainly made to earn his belt, having beaten Yoel Romero, one of the division's most fearsome competitors, in his last two fights roughly a year apart. In fact, Whittaker is responsible for two of Romero's three career losses.

"Yoel gave me his best in 10 rounds and couldn't put me away," Whittaker said. "I went 10 rounds with 'The Monster' and no one else has."

He laughed: "It is refreshing to have a different opponent other than Yoel."

Whittaker is currently enjoying a nine-fight undefeated streak which stretches all the way back to 2014 and the champ credits his team for his incredible success.

"My team is the best in world, my coaching staff is the best in the world," he said.

Whittaker admitted he felt more pressure fighting in his home country but he was trying not to let the expectation affect him and, instead, focus more on the positive aspects of the event.

"My most memorable fight was in Rod Laver [against Derek Brunson] so I'm expecting Sunday to go off," Whittaker said.

"The energy from that stadium and the crowd when I walked out last time, you could feel it, so it was unreal.

"The biggest thing I can say is I'm relaxed, it feels great, I was at my house until yesterday with my kids and I feel really, really good."

Whittaker believes that as the champion he shouldn't have to fight anywhere else but Australia.

"Travelling abroad is a nightmare, it affects everyone differently, you get the ones that are like, 'I flew in yesterday and I feel great'. Yeah, cool. Not me," he said.

Gastelum made a bold prediction that he would knock Whittaker out in the first round, but Whittaker intimated the challenger might end up eating those words.

"He might, but a lot of other people have said that. There's a club," Whittaker said with a smile.

Whittaker concedes Gastelum had embarked on a similar journey on the way to this meeting.

"He's beaten some big names, he's young, he's hungry, he's tough, he hits like a truck, he's a got a good, well-rounded skill set," he said.

"It's definitely not a step down [from Romero]. I respect his abilities, he's a dangerous fighter, he's going to come in there hungry with nothing to lose – one of the most dangerous combinations.

"I think we go in there very, very, very, very even, it's just I'm going to bring the best Robert Whittaker to date on Sunday, and I'm dangerous on a bad day."