Ed Sheeran sings during Bruno Mars' birthday celebration

How do you celebrate a birthday if you're a multi-award winning pop star? You ask another best-selling music artist to serenade you, of course.

That's exactly how Bruno Mars celebrated turning 33, 'hiring' Ed Sheeran to sing for him.

Mars shared the video on Instagram, sporting his trademark sunglasses and a gold birthday hat, all while he enjoyed several cup cakes which spelt the word 'BRUNO' and Ed sang happy birthday.

The video was posted from backstage at Bruno's '24K Magic Tour in Nashville, USA. Once Sheeran had finished singing, Mars ordered him to sing "again."

Back in August, Ed Sheeran hinted at an upcoming musical project with Bruno Mars. Somehow, we don't think this was it.

Pictures from Instagram : brunomars