Ellen DeGeneres, queen of daytime TV, stopped by The Tonight Show on Wednesday to give reigning late-night king Jimmy Fallon a lesson in lip sync battles.
Of course, all royal competitions need a judge – who better to preside than Justin Timberlake?
The pair valiantly fought their way through performances of songs by everyone from Diana Ross to The Killers, but in the end there could only be one winner.
Who emerged victorious?
Watch the full video above.