Mancini has a chance if he can last until the late rounds... problem is I dont think he would. He was too easy to hit, and although he had a good chin... so did Bramble... Chapo KO 5.
Smart money says Chapo finds Ray's chin and ends things, but just for giggles before we see the "Durrrr, glorified clubfighter durrrr" brigade we might consider that the way to beat Rosario was to crowd him and smother his punches, like Ramirez did, or Chavez, or later Hiranaka. That was obviously Mancini's game. Just sayin'....
Mancini certainly wasn't a club fighter (that's Gatti), and I do give him somewhat of a chance here. But Rosario is the solid favorite.
I think it's a great plan - as I recently watched and scored Rosario's first fight with Ramirez. The only caveat is one must possess a Ramirez-like jaw. Ray's was good but not Ramirez-like. I see Rosario tagging him during this encounter and that would be it. Not one-punch KO, but that would be the beginning of the end.
I like Mancini's body punishment and workrate to have Rosario backing up and being forced to the ropes. I think the body shots do him in and he hangs tough for awhile but gets stopped somewhere after 8 rounds.