He told We Love Pop magazine: "It was more like - everyone's got my hair now and I need to change it up a little bit! Once I had my hair, I felt everybody else started to do the same thing, so I decided to
Pointing at a picture of Liam, he added: "I mean, does that look a little familiar? Just a touch!"
Despite Liam copying his hair, Justin is thrilled to be working with the group - which also includes Niall Horan, Harry Styles, Louis Tomlinson and Zayn Malik - on their eagerly awaited second album.
He said: "The One Direction guys are great. We have a lot of fun whenever we hang out. They came over my house and we were just chilling out around the pool and listening to music.
"We were talking about me collaborating with them on a song on their next album. It's gonna be great."