One Direction reaffirmed their domination over America last night (December 19) with a performance on X Factor USA.

The group ran through their new track 'Midnight Memories' to a delirious audience on what was the final episode of the TV talent show's series.

It prompted a standing ovation from the judges, including Niall Horan's long-term rumoured love interest Demi Lovato.

It was loved-up duo Alex and Sierra who ultimately won on the night, beating Jeffrey Adam Gutt.

The show's official account tweeted: "There you have it folks...Love wins!!!!! @AlexandSierra3, #WINNING #xfFinale."

Alex and Sierra meanwhile follow in the footsteps of 2012 winner Tate Stevens and 2011's Melanie Amaro.