TMZ Sports spoke with Luke -- the former UFC middleweight champ who's moving up to light heavyweight -- and he ain't switching divisions just 'cause cuttin' weight sucks.
He wants to fight Jon Jones.
"I'm a different man at this weight, with the power behind me. I'm moving up to get after him. So, that's what I'm here for."
Luke's just the latest to throw his hat into the super crowded "I wanna fight Jon Jones" ring. Earlier this week, Anthony Smith AND Corey Anderson also told us they want a crack at Jones.
But, Rockhold's got the best resume of the 3 fighters ... and a fight with him and Jones would be a big money maker ... and it's a match L.R. is totally confident he'll win (he told us he'll be champ in '19).