One Direction Still Amazed By 'Mind-Blowing' Success

Sure, One Direction just wrapped up a hugely successful U.S. tour, but that doesn't mean they don't already have their even more enormous 2013 world tour on the brain.

As soon as the guys take a bit of a summer vacation and hit the studio to work on their sophomore album release, they will turn their attention to the highly-anticipated jaunt, which kicks off abroad at the beginning of 2013 before heading back to the U.S. just in time for summer.

"To be honest, if you had said to us a year ago, and this sounds so cliché, [but] if you had said to us a year ago that we were gonna be touring America, we would absolutely have fell on the ground laughing at ya," Niall Horan told about how quickly 1D have become popular all over the world.

"Obviously when the record label and stuff wanted to send us to America just to see how it would go, no one, not even them, had an idea of how it was going to go," he added. "And self-admittedly no one could tell how it was going to go. So to think that we're going on a world tour next year and about 85 percent of it is sold-out already is just mind-blowing."

It's a good thing that Niall and the boys have some downtime before they hit the road, since he's still trying to wrap his head around his inevitably busy 2013. The guys have a few one-off shows at the end of this year, before the tour kicks off at London's O2 Arena in February. They will swing around the globe before landing Stateside again on June 13 in Ft. Lauderdale, Florida. "I don't know how we're gonna do it," he said, before adding that the guys will do "what we be doing, I suppose, and hopefully it all works."