After the challenge that shook the rock-comedy world, the agreement that set the whole thing in motion, and the last-minute blast of trash talking, the long-awaited drum battle between Chad Smith and Will Ferrell finally went down on the 'Tonight Show' last night (May 22).

To start things off, the squabbling doppelganger duo sat down with host Jimmy Fallon for an interview segment, during which Ferrell and Smith pretended to be one another and "Smith" -- drinking from a cup of what he called "Chad Smith go juice" -- "remembered" hearing about their much-vaunted resemblance while he was "jamming with the Chili Peppers" and deciding he needed to settle the issue after his bandmates told him, "We're starting to get brainwashed. When we look back, we think that's Will Ferrell playing drums."

Added "Smith," "I'll be honest, I'm a little high right now."

That pretty much set the tone for the resulting battle -- which, as promised, worked in some surprise twists, including an ending that recalled Ferrell's 'Saturday Night Live' past and drove the studio audience wild. What did they play? Who finally won? We don't want to spoil any surprises, but you can watch it all unfold in the clip we've embedded at the top of the post.