Justin Bieber is ''hurting big time'' over Selena Gomez.

The 'Baby' hitmaker is reportedly upset over the rumours that his on/off girlfriend is dating music producer and DJ, Zedd, after the pair were spotted holding hands at a Golden Globes after party.

A source shared: ''Justin is going to act like he doesn't care one bit, but in his inner circle, everyone knows he's hurting big time over the fact that Selena is with Zedd.''

The 20-year-old singer is believed to be ''shocked'' about his ex's rumoured relationship but is confident he won't be replaced.

The source added: ''No he does not think Zedd will replace him.

''He's shocked that she's with Zedd, to the point where he's been saying he thinks it's fake, that they're doing for attention.''

The new relationship is ''threatening'' the ex-couple's chance of reuniting, with an insider revealing that Zedd is exactly what the 'Come And Get It' hitmaker is looking for.

The source told HollywoodLife.com: ''Yes, Zedd is a threat to Justin. He's super talented and successful. He's got a ton going on and he's just a nice guy, with an awesome sense of humour.

''Plus, he's sensitive and quirky and Selena likes that kind of stuff in a guy.''