Robert Whittaker reckons if every UFC fighter were put into the same room, and told only one could leave, he already knows which guy makes it out.

“Which for me, is how you judge pound for pound,” he says.

“If everyone eligible is put into a room, who wins? Which dude beats everybody else?

“Although pound for pound, weird concept.

“Because fights are different in different divisions.

“The way flyweights fight, for example, isn’t the same as the way middleweights fight.

“And neither of them are the same as heavyweights.

“Which is why I’ve never really understood the concept.

“And why those UFC rankings are done by people smarter than me.

“But if I’m asked what it means, it’s if everyone eligible gets put into that same room, who is the one who beats everyone else?”

So who makes Whittaker’s door?

“Has to be Jon Jones,” Australia’s first UFC champion tells Fox Sports Australia.

“Has to be.”

All of which brings us to UFC 285 this Sunday.

When after three years gone from the Octagon, Jones finally returns for not only his hyped UFC heavyweight debut, but a championship showdown against Frenchman Ciryl Gane.

Entering the title fight as a $1.60 TAB favourite, Jones is looking to become just the eighth fighter in UFC history to have claimed belts in two divisions.

But what about regaining his pound for pound crown, too?

Currently, that spot is held by Australia’s own Alexander Volkanovski.

The reigning UFC featherweight champ who performed so well when losing to Islam Makhachev last month at UFC 284, he kept top spot ahead of the lightweight champ.

Which is itself a debate still being contested among fight fans.

Just as it surely intensifies Sunday if Jones wins, too.

Indeed, when it comes to the P4P debate, opinions differ not only on the UFC rankings themselves – but exactly how the whole thing is put together in the first place.

Which is why Whittaker has absolutely no problem with any list that has Volkanovski No.1 – “the guy’s a powerhouse, can do it all” – but says his own method of picking mixes things up slightly.

“Who’s the one dude who beats everyone in the world -- that’s it for me,” Whittaker says.

“And Jones, he’s probably the best to ever do it if I’m being honest.

“The guy is phenomenal.

“And I don’t think there’s another fighter would contend that, either.”

Despite having not stepped into an Octagon for three years, Jones currently sits No.10 on that pound for pound list he once dominated.

So where he would he now go with two UFC titles? Who can claim to sit above him for GOAT? And what, if any, weight is attributed to those PED sagas shadowing his storied career?

Speaking with journalists at Thursday’s UFC 285 media day, a bulked up Jones revealed that, given his own inactivity, and the incredible rise of Volkanovski to arguably the greatest UFC featherweight ever -- among a list including the likes of Jose Aldo, Max Holloway and Conor McGregor -- the Australian deserved to be atop the current UFC P4P rankings.

However soon after, and having joked about Volkanovski’s dancing in a Youtube clip, the American added that he had bigger goals than P4P.

“I’m fighting to be the greatest fighter ever,” he said.

“Not to be the pound for pound best right now.

“We have two different motivations and I think there is room for both of us at the top.”

On Volkanovski he also said: “I do believe he deserves to be the best in the world.

“Him and Islam

“Alex kept that title after the (Islam) loss, and he deserves it.

“He’s refreshing, he speaks well, his country loves him.

“He just can’t dance.”

Elsewhere, Jones revealed that while he looked different now – “I don’t have a mean six-pack like I used to” – he was also coming off an “awesome” camp where he had knocked sparring partners out.

“The MMA game is wild,” he said. “I have young men coming up to me and they’re like ‘dude, I started watching you when I was 10 years old, now I’m 22’ .

“I’ve been around a long time.

“I’ve got all these grey hairs in my beard, it’s wild.

“And I’m honoured to still be here

“I’ve been inactive over the last three years when it comes to the UFC space.

“I’ve been living a martial arts lifestyle for the first time in my life.

“I have my own team and they hold me accountable.”

Accountability, of course, is something long attached to the Jones storyline.

Apart from enduring a string of unwanted headlines outside the cage, Jones has also twice popped for performance enhancing drugs and been stripped of titles.

During a recent interview with the MMA Hour, retired UFC star Chael Sonnen even claimed Jones was also juicing for their own 2013 showdown at UFC 159.

And Sonnen knows, he says, because he was also carrying “more juice than Tropicana”.

Asked by Ariel Helwani if Jones was clean when they fought, Sonnen laughed: “Heavens, no.

“Oh my god Ariel, we know our own.

“I had more juice than Tropicana and he pushed me around like a Mack truck.

“As soon as we locked up with each other, he’s pushing me backward before his big spinning elbow … I remember thinking, ‘I know your secret because I got the same one’.”

While Sonnen said there was testing at that time, “it was an IQ test, not a drug test”.

“We didn’t have USADA,” he continued. “So they had to tell us when they would come and test.”

Sonnen eventually failed a drug test the following year, while Jones would then do the same in 2017, his second positive – which also saw him stripped of the lightweight title won against Daniel Cormier.

Jones also suffered a doping violation in 2016, which saw him removed from UFC 200 and stripped of the interim lightweight title.

Aside from all this, to enter the pound for pound debate Jones must first get past Gane, who is himself coming off a KO win over Australia’s Tai Tuivasa last September.

“(But) I’m not Tai Tuivasa,” Jones told the media on Thursday.

“I look nothing like him, don’t perform like him.

“I’m not Derrick Lewis, I’m not Francis Ngannou, I’m a much different athlete

“I’m by far the most versatile athlete he’s ever faced.

“The most experienced.

“And he will realise that by round two, or round one.”