The pair ripped through more than 20 rap classics, starting with LL Cool J's "I'm Bad", before doing snippets of tracks by Run DMC, the Beastie Boys, Tone Loc, Outkast, Jay Z and more.

Timberlake was the lone guest on the final night of the first week of Fallon's new gig as Tonight Show host; the show moved back to New York this past week after more than 40 years in Los Angeles and following the recent retirement of Jay Leno.