Watch Little Mix serenade Nathan Sykes for his birthday last night.

Nathan is currently the special guest on Little Mix's massive 'Get Weird' Arena tour.

And last night backstage the girls surprised Nathan with a cake and their rendition of 'Happy Birthday' to celebrate his 23rd birthday.

Watch the video here:

https://amp.twimg.com/v/58a93367-768a-448b-b139-dc46aa183b5d