Selena Gomez is on ''cloud nine'' with Zedd.

The 'Come And Get It' hitmaker - who is rumoured to be dating the 25-year-old music producer and DJ after the pair were spotted holding hands at a Golden Globes after party on Sunday night (11.01.15) - is reportedly completely ''smitten'' by her new love interest.

A source shared: ''Selena is on cloud nine. She's never been happier and definitely has Zedd to thank for that. She's absolutely smitten with him.

''First off, Selena feels like he totally gets her on so many levels. They never run out of things to talk about it. One night they stayed on the phone for four straight hours talking. It's crazy.''

Meanwhile, the new rumoured relationship is reportedly affecting the 22-year-old singer's on/off boyfriend, Justin Bieber.

The 'Baby' hitmaker is said to be ''hurting big time'' over the news that Selena has found someone else.

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...

''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.''

Zedd's ''sensitive and quirky'' nature is reportedly worrying the 20-year-old singer because it's what she is looking for in a boyfriend.

The source added to 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.''