More Justin Bieber Babygate Silliness

As we first reported, Mariah's ex Robbie Powell claims he's positive he's the real father of her child -- not Justin Bieber -- and he's willing to cough up the DNA sample to prove it ... because he's tired of Yeater using the kid for publicity.

But Mariah's lawyer Jeffrey Leving says Robbie's just playing into the media mayhem surrounding the story -- telling us, "If Robbie Powell 'actually' believes and claims he is the father, I suggest he contact me directly. Litigating this case in the media and bypassing Mariah's legal team only perpetuates the three-ring circus and accomplishes nothing as I see it."