One Direction are back with a new sound, a new song, but the same swoon-worthy lyrics that have Directioners melting at their feet.

On Monday, the guys officially released "Steal My Girl," the first single off their upcoming album Four, an upbeat, classic-rock vibe of a song that has all the girls trying to figure out exactly who that "queen since we were 16" really is.

MTV News caught up with co-writer Julian Bunetta, who has helped pen 1D's "Best Song Ever" and "You & I," and he revealed that there's actually more than one girl who inspired the track.

"There are a few meanings behind it ... there is the one that speaks to the bigger picture of them and their fans, and there is the one that speaks to the actual person in your life, and that was very intentional," he said. "It's based on everybody's experience: you have six guys in a room that have all been in love before and we all have jealousy -- some are better at hiding it than others, but we don't like when people hit on our girlfriends."

He continued, "But it was more of a joyous thing, it just speaks to how happy you are with this person. If you have something great, everyone is going to try and take it from you. And that also speaks to the fanbase, I think, 'cause of other groups [trying to steal the 1D fanbase] ... there are a lot of layers."

Julian, who co-wrote this song with Liam and Louis, did reveal that the idea behind the song didn't come together because the guys were all swapping love stories -- it happened pretty randomly.

"I think, if I recall correctly, we were playing a drum beat and it just sort of came out," he recalled. "Somebody said that line and it was like, 'Woah, yeah I relate to that,' and we all looked around and was like, 'Yeah, I like that, I can totally relate to that.' "

The song is now #1 on the iTunes songs charts and, not surprisingly, it was instantly loved by fans. But many critics couldn't help but notice the similarities between the piano opening of 1D's song and the classic Journey ballad "Faithfully," something Julian wasn't even aware of until he read the song reviews.

"When we sat down and played the piano lick, nobody had any references in their head about what they wanted to write or anything and then I saw all the things about that [Journey song]," he said. "At the end of the day, the lyric and the melody have nothing to do with any other song that I have ever heard. Sometimes there's only so many things you can do with a piano at that tempo.

"There is an age-old saying that great minds think alike so, naturally, sometimes people are going to write on the same inspirational wave lengths and come up with things that are similar and it wasn't anyone's intention to do that at all...

He added, "But at least we are being compared to a classic song and not a sh---y song, so that's a compliment."