"Justin Bieber showed up with like 20 guys... Backstage is a very small, constructed place, he had a guy holding a slice of pizza, a guy holding a Diet Coke. You were trying to fight around all these people to get dressed. Timberlake, it was just him. He's a real class act, that guy." Funnyman Bill Hader weighs up the Justins as guest hosts of U.S. comedy show Saturday Night Live.