Justin Bieber is so over!  Well, maybe not yet, but there’s a new tween dream band on the block that’s poised to make the Biebs a has-been at the ripe old age of 19.

We’re talking about One Direction, five perfect looking, perfect sounding guys from Ireland and the U.K. who made a big splash on Simon Cowell’s X Factor in London a couple of years ago, and have gone on to much bigger and better things since.  Now they’re storming the U.S., and young girls all over the country are going bananas.

On Monday morning they made their American TV debut on Today.  Hundreds of crazed girls and their poor parents lined up for hours to grab a prime spot to see them perform, and judging from video of the performance they weren’t disappointed.

The cute blond thing in the band is one Niall James Horan, an 18-year-old dreamboat from Mullingar, Co. Westmeath.  He idolizes Michael Buble, has played the guitar since he was a child, and has more than 1.8 million followers on Twitter already.

Horan first auditioned for X Factor in 2010 as a solo act but didn’t make the final cut. But that turned out to be a stroke of good luck. The four other members of One Direction also bombed as soloists, but the show’s producers decided to group them as a boyband and a new sensation was born.

They are huge in the U.K. and Ireland, so much so that the recently beat out the mighty Adele for Best British Single at the Brit Awards, the U.K. equivalent of the Grammys.  Their debut CD for the American market, Up All Night, features the top-selling single “What Makes You Beautiful,” and contributions from the likes of Kelly Clarkson, a fellow reality show TV alum.

As if all that’s not enough, the band – known as 1D for short – scored a coveted slot as the musical guest on Saturday Night Live on April 7. And Bieber’s manager Scooter Braun says his guy just might team up with the latest Fab Five.

“Very possible,” Braun says. “(Justin) likes them and thinks they are good dudes. “

Horan isn’t exactly intent on spreading Irish culture in a modern, 21st century way, though. The band will be in Philadelphia on March 17 and Horan, a constant tweeter, wants his fans to do him a favor.

“I need your help, everyone needs to come dressed as leprechauns,” he tweeted on Sunday. “Let's make our own St. Patrick’s Day parade in the mall. Since I’m not home that day, we’re bringing Ireland to the USA.”

Leprechauns? Dude still has a lot of learning to do about real Irish life, apparently!

Here, catch One Direction's performance of 'What Makes You Beautiful' on the Today show:

And here, catch their interview and performance of 'One Thing':