One Direction 'X Factor USA' Video: The Boys Perform 'Little Things' And 'Live While We're Young' Live!

Tonight, the students became the masters on "X Factor." One Direction made a guest appearance on the American version of the show to perform "Live While We're Young," "Little Things," promote their partnership with Pepsi, and, most importantly, send the audience into mass hysteria. Even though it's only been 2 years since they were contestants in the UK, the boys looked like pros on the "X Factor USA" stage.

1D opened the episode with a dance-around-your-living-room-worthy performance of "Live While We're Young," the first single off their upcoming album, "Take Me Home." Notable moments included phone booths, balloons, and a sneek peak at Liam's new tattoo on his arm -- which looked like 5 arrows pointing in one direction. No further explanation necessary.

Later in the show, they sang their newest single, "Little Things," a stripped-down, uber-romantic track penned by their pal Ed Sheeran. Unsurprisingly, it was an up-close-and-personal vibe, complete with a dimly-lit stage and many long, mournful gazes from the boys. (Zayn, we're looking at you.) However, the live version of the song actually felt very adult, and we'll even venture to say they gave one of the strongest showings vocally we've ever seen from them.

Watch the videos ("Little Things" above, "Live While We're Young" below) and let us know how you think they did in the comments.