Ed Sheeran admits he was initially 'wary' of working with Pharrell

Ed Sheeran has revealed that he had his doubts about working with Pharrell Williams.

The US star produced and co-wrote the Brit's recent single 'Sing', which hit No.1 in the UK.

However, the 'A Team' man told The Sun that working with Williams took him out of his comfort zone.

Sheeran said: "Working with Pharrell was a different way of writing a song for me. It was completely new but a good way of writing. He brought in the bass, hook and the drums and then I wrote all the top line. I was wary at first but now I am really happy about that song."

Speaking meanwhile about working with the renowned producer Rick Rubin, the singer-songwriter added:

"Rick came in late. He came to gigs and expressed an interest but it was only in August when he invited me around his house in Malibu. I had my guitar with me and he asked me to play and I work best in those situations where you want to impress. He reassessed where I was with the album and came on board. He took all the bulls**t away and made me play all the songs as live and kept the raw element to the album."

Sheeran is due to release his second album 'x' on June 23.

Watch Ed Sheeran's 'Sing' video below: