It's Jack Black vs. Michael Bublé, in a Battle for Best Singer of All Time (VIDEO)

"You guys know each other?" Jay Leno said. Yeah, they've met before. And they've got a bit of a rivalry going on. And so, on the new 'Tonight Show' (11:35PM ET on NBC), the two legendary singers of our generation -- Grammy Award-winner Michael Bublé and, um, Jack Black -- squared off in a battle for supremacy.

The two vocalists recalled a previous "sing-off" encounter that they had on an Australian talk show. Next, inspired by Black's performance in 'School of Rock,' the pair tried to determine who was more "hardcore" -- singing-wise, that is. Because really, you're not hardcore ... unless you live hardcore.

So, who would be the winner? Well, to be honest, they were both a little off-key, as Bublé screeched awkwardly in an effort to imitate Jack's, um, soaring vocal abilities.

Still, we're going to tentatively declare professional singer Michael Bublé the winner of this particular contest. Better luck next time, Mr. Black! So, Bublé beats Black. But hey, you know what we've always wondered? ... Who would win in a battle between Michael Bublé and one of the velociraptors from 'Jurassic Park'? Okay, we've never actually wondered that. It just gives us an excuse to provide this very random link.