(Cover) - EN Showbiz - Katy Perry has "undeniable" chemistry with John Mayer, it has been revealed.

The pop singer has had an on-off relationship with Hollywood lothario John since they got together earlier this year. It has been reported that the pair are currently very much 'on' after their recent public appearance in New York for John's 35th birthday bash.

"Though they've had their ups and downs, Katy and John are smitten with each other," a source told British magazine Grazia. "They've got undeniable chemistry."

Katy has a history of being able to tame some of the biggest celebrity players. The star managed to convert womaniser Russell Brand into a dedicated husband for 14 months while they were married. Sources have revealed Katy succeeded in pinning down John by jokingly playing him at his own game.

"Katy wanted to show John that she won't stand for any of his nonsense. She even bought him a box of Godiva chocolates, just so he'd know what it was like to be romanced by a girl," the source continued. "John thought it was really funny." (C) Cover Media