Ryan Garcia says he's "100% sure" he'll knock out Luke Campbell in the first 3 round of their January fight ... adding, "I'm very, very, very sure of that."
King Ryan talked all sorts of trash about his opponent on Kevin Hart's "Cold As Balls" YouTube series ... explaining why he believes the fight could propel him to global stardom.
In fact, the 22-year-old told Hart it's downright "the biggest fight of my life so far."
"This is going to put me on, you know, that level where I get that respect," Garcia said.