Justin Bieber has met up with One Direction stars Niall Horan and Zayn Malik as the boyband spend time in the US in preparation for the MTV VMAs.

The British group are performing the awards ceremony in Los Angeles tomorrow (September 6) and it seems they haven't taken much time in meeting up with their famous friends.

Bieber's manager Scooter Braun tweeted about a rendezvous his client had with the two One Direction lads - something that he reckons will cause "teenage girls' heads to explode". He said:

"So @justinbieber @niallofficial and @zaynmalik are all hanging out and @alfredoflores is the coolest. and now... teenage girls heads explode."

Braun later added: "These kids make me feel old. very very old. hahaha. a friend just hit me and said... "u feel old? i dont even know who the people you're tweeting about are." #classic #WeAreOld."

Zayn Malik meanwhile tweeted soon after: "LA is definitely one of my favorite places to stay love this place :) x"

Horan and Malik's bandmate Harry Styles has been riding the waves it seems on his downtime, tweeting the phrase "surf's up" with a photo of some water suits.

Watch Justin Bieber performing live below: