Smokin' hot UFC Octagon girl Arianny Celeste says she's TEAM NATE DIAZ when it comes to the big fight -- all because the Diaz brothers are "crazy as f***."
Celeste spends A LOT of time around the fighters -- and says she's convinced Nate is gonna beat Conor up ... plain and simple.
"[The Diaz brothers] remind me of my family," Celeste says ... "They're crazy as f***."
The news is gonna piss off Conor -- who told off ALL Diaz supporters Thursday night in a Tupac "Hit 'Em Up" style rant.