Smith, the drummer for the Red Hot Chilli Peppers, and the funnyman dressed in matching jeans and Kiss t-shirts for their appearance on the show. After clarifying to host Jimmy Fallon who was who the two stepped to the stage to battle for the title of greatest drummer on the Tonight Show.
In the end, Ferrell came out victorious and took home the giant golden cowbell prize.
Ferrell and Smith, who are often mistaken for each other, agreed to participate in the competition after the actor was asked about his resemblance to the drummer during an Ask Me Anything Reddit session earlier this year.
"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," Ferrell said at the time. "The truth of the matter is there is no Will Ferrell. Only Chad Smith."
You can check out a clip of the duo's battle below.