Earlier this year, Ferrell participated in an "Ask Me Anything" forum on Reddit, and was asked by a fan at one point about his resemblance to Red Hot Chili Peppers drummer, Chad Smith.
"It has been acknowledged many times that myself and Chad Smith, drummer for the Red Hot Chili Peppers, share a resemblance to each other," Ferrell wrote at the time. "A lot of people think that it's me playing for the Red Hot Chili Peppers. But that would be an insult to Chad Smith. The truth of the matter is there is no Will Ferrell. Only Chad Smith."
Smith, 52, jumped on to challenge Ferrell to a drum battle, telling the actor, "I've seen your skills; you don't got 'em."
The showdown took place on The Tonight Show on Thursday, May 22, when the actor and the musician started the sit-down with Fallon impersonating one another. The men wore matching outfits of jeans, backward caps, leather jackets, and T-shirts and shared the couch next to Fallon's desk.
Ferrell spoke of Red Hot Chili Peppers' "jam houses" as Smith and improvised interactions with RHCP bassist Flea. For his part, Smith spoke as Ferrell. The two then staged an old-fashioned drum-off.
Watch the hilarious video above!