Forget the Pacers ... the Cavs are gonna smash on EVERY NBA TEAM standing in the way of their quest for another ring -- so says UFC heavyweight champ Stipe Miocic.
We got Stipe -- a proud Cleveland native -- after the LeBrons got rocked in Game 1 of their series with Indiana ... and he told us everyone needs to chill the hell out.
"They're fine. It's one game. It happens," Miocic told TMZ Sports. "They'll start smashing people."
Stipe was so confident, he even Guaran-Sheed the Cavs would crush any Western squad that makes it to the Finals (so, the Warriors or Rockets).
"It's my Cavs, of course they're gonna win."
We also spoke to the champ about the 'Ultimate Fighter: Undefeated' reality show he coached on that premieres Wednesday on FS1 ... and he told us why the fighters this season are must-see TV.