|Taylor Swift, Harry Styles|
A source told the Daily Mirror newspaper: "Taylor is a huge One Direction fan and was excitedly bopping along to the boys when they performed on stage. Then she was chatting to Justin and told him how hot she found Harry.
"Justin was joking about trying to keep his own girlfriend, Selena Gomez, away from the band because she too loves them. Taylor went backstage and was hanging around by the group's dressing room and said a quick 'hello' to the guys.
"She started dramatically fanning herself afterwards making out like she was overwhelmed which got everyone laughing. She really likes Harry but made Justin promise not to go on the record about it."
Justin has previously claimed the British boy band - made up of Harry, Zayn Malik, Louis Tomlinson, Liam Payne and Niall Horan - would be a huge hit with American girls
He said: "The single guys from One Direction are going to have a lot of fun.
"They look great, they sound great and, when you add their British accents into the mix, the American girls are going crazy for them.
"Sure you need the talent, but you need to win over the American public, that's what it is all about. One Direction are genuine good guys."