Mariah Carey has blasted reports she has fallen out with Janet Jackson and stalled a planned duet, insisting the collaboration was nothing more than a "concept" by producer Jermaine Dupri. According to Dupri, who is Jackson's boyfriend, the two pop divas have been planning to team up for years - but Carey insists that's not the case. She says, "That was Jermaine's concept... I love J.D., he's like my brother but he makes these things up and he gets an idea and then he tells the world."