Horan was not the only one star-struck though. The It’s Always Sunny in Philadelphia and former Cheers actor shows off pictures of "Troll Foot" meeting the band.
DeVito told Forbes last year about his "Troll Foot" social media presence. He says, "I like my iPhone. I tweet. I put my foot out on Twitter every day…not every day. When I see a picture that I really want Troll Foot to be in, I put him out."
"Steal My Girl" will be available in the UK on Sunday. The song is the lead single of their upcoming album, Four. Four will be released on November 17.
One Direction would never break up. Find out why in the video below.