Austin McBroom Guarantees He'll KO Bryce Hall Within 2 Rounds, 'He's Nervous!'

Austin McBroom says his celeb fight with Bryce Hall ain't gonna last too long ... telling TMZ Sports he's guaranteeing a knockout within the first two rounds!!!

"He won't last past the first round," the YouTube star said of his TikTok rival. "He'd be lucky to get to the second round. If he gets to the second round, it'll end right there."

The two social media titans are finally set to throw down in Miami this weekend after months of trash talk ... and McBroom seemed as confident as ever Friday that he'd score the win.

In fact, Austin seemed downright concerned for Hall ... telling us he's worried he might legitimately HURT Bryce on Saturday night at Hard Rock Stadium.

"He's nervous," McBroom said of Hall. "He's a nervous one. He's out there getting jitters face-to-face. He was out there shaking a little bit."

"So, I just hope he's ready man. 'Cause in this sport, you can get seriously hurt. And, I would hate to hurt the kid."

As for Bryce, he insisted he ain't feeling any butterflies ahead of the big boxing match ... and told us he's actually received some key advice from Logan and Jake Paul about managing all that.

Oh, and he threw a fat jab McBroom's way.