Singing is best side job: Gwyneth Paltrow

Actress Gwyneth Paltrow, who performed back-up vocals alongside country singer Holly Williams earlier this week, said singing is one of her biggest passions.

The 41-year-old actress, who split from Coldplay frontman Chris Martin after 10 years of marriage, said music comes a close second to acting for her, reported Contactmusic.

"Singing back-up, my favourite side job holly williams," she tweeted.

The actress surprised fans by jumping on stage with singer-songwriter Holly, who was supporting country rocker Jason Isbell, swaying from side-to-side in time with the music.

The 'Iron Man 3' star - who has children Apple, nine, and Moses, eight with estranged husband Chris Martin - will no doubt have picked up some tips from him.