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.