Justin Bieber serenaded Selena Gomez in a hotel bar on Friday (20.11.15).

Justin Bieber and Selena Gomez

Justin Bieber and Selena Gomez

The on/off couple were spotted at the Montage Hotel in Beverly Hills where Justin sang songs including 'My Girl' and his own tune 'Sorry' to the former Disney star.

Instagram user @eatprayphoto spotted the interaction and posted some videos, captioning one "When you're having a drink at an empty hotel bar and @justinbieber appears out of nowhere and begins to sing on the piano" and writing "@justinbieber singing my girl to @selenagomez....is this real? Pure magic (sic)" alongside another.

She also posted a picture, taken by Selena, 23, of her and some friends with Justin and revealed the bad boy singer couldn't have been nicer.

Alongside the picture of a smiling Justin, 21, she wrote: "Photo cred: @selenagomez. He asked to sit at our table to chat, so impressed by the kindness (and realness!) of this guy tonight. Now a #belieber (sic)."

Justin and Selena last split up in October 2014 after almost four years of on/off dating but he recently admitted he will always love the singer.

He said: "[She] is someone I love dearly. I'm never going to stop loving her. I'm never going to stop checking in on her. I don't think if you end a relationship, you should end that, unless it was super toxic and you guys were hurting each other physically or mentally. We always respected each other and we still respect each other."