Amanda Nunes is becoming a PPV staple. The UFC women's bantamweight champion is set to headline her second straight PPV event after defending her belt for the second time last September. But this time she'll attempt to do it against somebody she considers a friend: Raquel Pennington. 

But while they maintain a friendship outside of fighting, the two know it will be all business once the cage door closes on Saturday night in Brazil for UFC 224.

"This is a single sport, you can't think in group. You have to think about yourself," Nunes told CBS Sports. "That belt is in my house and I never want that belt to go anywhere. The motivation is that, keep proving I'm the best, keep proving I'm the champion and then we can be friends again."

Nunes also hasn't ruled out the possibility of making a run at becoming the first woman to simultaneously hold belts in two divisions, even though that's a conversation for after Saturday night.

"As long as I have contenders, I will keep fighting at 135. If something stop or I don't have any girls [to fight] anymore, then I have to make the next move in my life," Nunes said. "But now, I have Rocky, the other Brazilian that just beat Cat Zingano. The division is running and that's a good thing."

Can't get enough UFC? Subscribe to my podcast In This Corner with Brian Campbell where we break down everything you need to know in the Octagon.

Nunes and Pennington are getting all the attention in the main event, but there are several other fights of note to fight fans on this Brazil-centric card including a pair of legends squaring off in Vitor Belfort and Lyoto Machida, a perennial middleweight contender in Jacare Souza and a prospect in Mackenzie Dern. Let's look at the rest of the card.

FavoriteUnderdogWeghtclass

Amanda Nunes (c) -850           

 Raquel Pennington +525

Women's bantamweight title

Ronaldo Souza -150

Kelvin Gastelum +120

Middleweight

Mackenzie Dern -250

 Amanda Cooper +195

Women's strawweight

John Lineker -260

Brian Kelleher +200

Bantamweight

Lyoto Machida -280

Vitor Belfort +220

Middleweight

Karl Roberson -120

 Cezar Ferreira -110

Middleweight

Junior Albini -160

 Aleksei Oleinik +130

Heavyweight

Davi Ramos -155

 Nick Hein +125

Lightweight

Elizeu Zaleski dos Santos -130

 Sean Strickland +100

Welterweight

Warlley Alves -260

Sultan Aliev +200

Welterweight

Jack Hermansson -155

 Thales Leites +125

Middleweight

Ramazan Emeev -200

Alberto Mina +160

Welterweight

Markus Perez -305 James Bochnovic +235 Middleweight

With a big card on tap, our experts took a crack at picking each of the main card fights. Here are your pick makers: Brian Campbell (combat sports writer), Matthew Coca (producer), Michael Mormile (producer), Jack Jorgensen (editor) and Brandon Wise (editor). 

UFC 224 predictions        

FightCampbellMormileCocaJorgensenWise

Nunes vs. Pennington

Nunes

Nunes 

Nunes

Nunes

Nunes

Gastelum vs. Souza

Souza

Souza

Gastelum

Gastelum

Gastelum

Lineker vs. Kelleher

Lineker

Lineker

Lineker

Lineker

Lineker

Dern vs. CooperDernDernDernDernDern
Belfort vs. MachidaBelfortBelfortBelfortBelfortMachida
Overall (2018) 8-12-0 11-9-0 9-11-0 10-10-0 11-9-0

Campbell on why Nunes will win: The fact that Nunes enters as such a large betting favorite certainly has a lot to do with the fact that she's a more skilled fighter. But Pennington enters her first title shot with legitimate questions working against her. It has been 18 months since she last appeared in the Octagon and is fresh off a broken leg from a hunting accident late last year. Returning into the deep waters of a five-round fight is a lot to ask, not to mention being forced to deal with an opponent who is taller, longer and more dangerous. The days of questioning Nunes' cardio are over. Pennington may be tough enough to go the full distance but not skilled enough to win.

Jorgensen on why Souza will win: It was really telling to me in the second win over Brunson just how good of an all-around fighter Souza is. It's easy to focus on the jiu jitsu skills, but the man can put your lights out with ease at the same time. I care little about his age, if you have a fighter that can be that solid all around, then you have a dangerous man inside that cage. 

Gastelum's win over Michael Bisping was impressive, but Souza's skills will keep him in check, and I'll even go so far as to predict a KO win for the Brazilian in front of his home crowd in the third and final round.

Wise on why Machida will win: For as potentially ugly as this fight can be, I'll lean to the guy with a slightly fresher body. Machida enters his eighth bout at 185 pounds as a sizable favorite for a reason after shutting down one of the top rising prospects in Eryk Anders in February. While we would all love to see Belfort ride off into the sunset with a win, I've been fooled one too many times by these retirement fights to take the guy entering his final bout. Machida grinds out a decision victory here in "enemy territory."