Martina McBride has officially crossed over to the pop world, but as a songwriter! The country superstar has somewhat of an accidental hit with British pop/soul singer Joss Stone's recent tune, 'Karma.'

"Joss was recording in the studio with Dave Stewart (of Eurythmics fame), who we've come to know really well over the past year and a half," Martina tells The Boot. "I was writing with the Warren Brothers in the writer's room in another building. They started playing me this idea they had for me, but I said I didn't think it would work for me, but it sounds just like Joss Stone who is recording down in the studio. We worked on it for an hour and half and then took it over to Dave and Joss and tailored it to her, to what she wanted to say. The five of us wrote it together, and it's on her album. It's really cool."

'Karma' is the second single released from Joss' latest album, 'LP1,' which was co-produced with Dave Stewart. The two recorded the project in Nashville's Blackbird Studios, which is owned by Martina and her husband, John McBride.

Watch Joss Perform 'Karma' on 'The Tonight Show'