Rap superstar Nelly is planning a collaboration with singing superstars Janet Jackson and Mariah Carey. The Hot In Herre hitmaker has yet to convince the pop divas to join him in the studio - but he is refusing to take no for an answer, Jackson's producer boyfriend Jermaine Dupri reveals. Dupri tells MTV, "Nelly's got a crazy collaboration he's trying to put together, which is him, Janet and Mariah Carey all on one song. "That's what he wants. If he could convince them to do it, it would be crazy. He wants Janet to rap a 16-bar verse, he wants Mariah to sing the hook and he's gonna do two verses. He has it all planned out. You ask him about it! This is what he wants; he's 100 per cent deadlocked into it. "