Justin’s former NSYNC bandmate Lance Bass has claimed that the 'SexyBack' singer was never fully committed to ex-girlfriend Britney Spears - who he dated between 1998 and 2002 - because he was only interested in being a pop star.

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In his new autobiography, 'Out of Sync', Lance writes: "Britney showed no signs of the turmoil she would eventually encounter, maybe because she was so in love with Justin she thought it was going to last forever.

"I knew it wouldn't. Justin already had a great love in his life - his career. He wanted to be a star and no girl, no matter how great, was going to be able to distract him from that for more than a night or two between trips to the centre of the spotlight."

Lance also says that Britney was a "perfect girlfriend" and liked nothing more than hanging out with NSYNC in her pyjamas.

"At the time (2001), Britney struck me as just this adorable little teenage girl at a perennial slumber party, staying up late and having lots of fun.

"But as I said, she seemed like the perfect girlfriend, especially when she wore her pyjamas and hung out with the boys." he said.