The pair went head-to-head as coaches in the promotion's reboot of The Ultimate Fighter reality series currently airing each week ahead of a confirmed bout at UFC 266 on September 26.

It came after the first bout between the champion and No. 1 contender scheduled for last March was called off late after Volkanovski was found to have contracted COVID-19 in transit to the US.

The build up to that aborted first meeting was marked by a complete lack of animosity between the pair, but that's changed dramatically since shooting for the TUF series wrapped. Weekly viewers have seen the clear attempts from Ortega to get under the champion's skin ahead of their showdown.

While Volkanovski's rivalry with former long-reigning champion Max Holloway - in which he's currently up two-zip - has had the odd spark, the animosity with Ortega is now a roaring fire.

The Wollongong native admits the unique environment would make things tense with any rival, but Ortega has gone a notch above.

"I reckon, no matter who I was going to fight, you spend enough time with them and there'll be something there," Volkanovski said.

"We're competitive, I'm competitive. You're coaching against each other the [other] guy thinks he's a better coach than you, you're competing against each other.

"It's always going to happen through the process, you're always going to get annoyed at the person. But then you dive in deeper, [Ortega] plays this type of [nice] guy and that's just not what I saw.

"He's fake. He plays this caring, respectful, nice guy when I just think he's a selfish, unprofessional guy who doesn't give a shit about anyone but himself.

"I'm glad we've got a date now because it's been way too long since I've been there. I am going to make it to the octagon this time, I guarantee it. I'm getting in there and making sure nothing gets in the way of getting my hands on him."

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Volkanovski says there's no hiding the fact that being at such close quarters for such an extended period with a looming opponent is a unique build-up, but one he's used to his advantage.

"It is definitely different because [normally], even if there's no animosity, there's a lot of unknowns," he said.

"You don't know how they think or what their thought process about the game is. [Through TUF] you get a little insight into things like that in watching these episodes roll out.

"You see what they say, the way they coach, what they think about certain fights. You get that type of insight to their thought process and how they think about the fight game and what level they're on.

"I get a read on that. He says things about certain fights and I'm thinking 'mate you're looking for the wrong things'. It's good to see that he looks at things a certain way, while I'm looking on a way deeper level."

The 32-year-old says the cerebral approach proved beneficial as he looked to ease his way back to full fitness post-COVID - the result being an even more dangerous prospect.

"After COVID and not being able to train so hard, we had to work game plans for these guys [we're coaching]," he said.

"I'm away from my family over there with nothing but time on my hands. I'm understanding other guys and what they do, how we capitalise on this guys weaknesses.

"I'm drilling, technique after technique, 24-7. There's a lot of things I was really able to fine-tune, really get a deeper understanding of. I'm on a whole other level now.

"Talk's cheap, but I know when I go out there people are going to see it. There were a lot of things I did well, but now there's things I'm doing even better.

"I was the champ, I was already the best. Wait and see the damage I can do now."

The UFC 266 card in Las Vegas shapes as a blockbuster, with flyweight phenom Valentina Shevchenko to defend her title against former Invicta FC bantamweight champion Lauren Murphy in the co-main event.

Veteran crowd-pleasers Robbie Lawler and Nick Diaz will also throwdown in what will be the latter's long-awaited return to the UFC in a rematch of their UFC 47 thriller 17 years ago.