Alex Pereira Says He Wants To Fight At Heavyweight, Win Third UFC Title

Alex Pereira knows he has his hands full on Saturday with Khalil Rountree ... but, the UFC's light heavyweight champion also has his eye on a future goal that'd put him in a class of his own -- winning a title in a third weight class.

It's never been done before. There are fighters who have been champions in two weight classes -- some even at the same time ( Conor McGregor , Henry Cejudo , Daniel Cormier , Amanda Nunes ) -- but no fighter has owned belts in three.

If anyone can do it, it's likely Poatan ... who TMZ Sports asked this week about moving up to heavyweight after his main event scrap with Roundtree at UFC 307.

"I made it clear that I would like to go for my third belt. Now it's up to the organization. I already said what I want. Let's see what happens," Pereira told us through his translator/trainer Plinio Cruz .

Of course, Jon Jones is the current heavyweight champ, and Tom Aspinall the interim champ. Bones is set to fight Stipe Miocic at UFC 309 in November. Aspinall is the backup fighter. Assuming Jon and Stipe go off without a hitch, the plan would likely be to unify the title, pitting Jon/Stipe vs. Tom.

Could the winner then face Pereira? It's possible.

If it happens, Alex believes he has the "size for that, technique for that, style for that, and enough experience" to beat the best heavyweights.

But, first things first ... we also talked to Alex about Khalil, a powerful and experienced striker with one-punch knockout power.

We even asked AP about Jake Paul ... after The Problem Child called Pereira out after his last boxing match. The guys even FaceTimed in the ring.

Could we ever see Pereira vs. Paul?

We also talked to Khalil ... who says he's ready to prove he's the baddest man walking the planet.

Check out the full interviews! UFC 307 goes down on Saturday!