John Mayer Hails Katy Perry's New Song 'Roar' As An "Incredibly Big Song"

15 August 2013, 10:00 | Updated: 15 August 2013, 10:03

The 'Part Of Me' singer's boyfriend says he knew her song was a hit the first time he listened to it.

John Mayer says he knew Katy Perry's new song 'Roar' would be a "megaton bomb" hit as soon as he heard it.

The 'Your Body Is A Wonderland" singer says the track is "so big" and admits he felt privileged to be able to watch Katy at work on the song, her lead single from new album 'Prism'.

"I remember hearing it, going like 'Wow what an interesting experience' to hear something that you identify as massive before it's massive," John told Billboard this week. "I though it was a really sweet, unforgettable sort of experience to hear someone's work while they still have a very nascent relationship with it.

"In a way you get swallowed up by it, it's so big," John explains, while reviewing the song. "Because it's such an incredibly big song that it doesn't need you to tell anybody. Million of people are going to be dancing on tables to that.

The US singer-songwriter also opened up about his new collaboration with Katy on a song called 'Who You Love' from his new album, and reveals that Katy wrote her own verse for the track.

Check out a picture of Katy Perry out promoting 'Roar' this week below (Credit: PA):

"It was a really fun opportunity for her to write like, her answer to [the song]," he added. "So you get these two sides to this relationship that are brutally honest but no less universal."

John Mayer's new album 'Paradise Valley' drops on 20th August while Katy Perry releases 'Prism' on 22nd October.