I think this goes the distance, or maybe there is a late stoppage involved due to exhaustion on the part of one or the other. I'm leaning with Mercer, who I think is tough enough to survive the two good rounds Tyson still had in him, and maybe to slowly wear Mike down late, just enough to edge it on the cards. Bur Mercer was about as shot as Tyson, so who knows? Neither guy had much of a workrate at this stage of their careers.