I don't think of Mayweather vs Oscar for some reason when I think of Mayweathers chance of beating Manny, I think of Mayweathers fight with Hatton more so.
Hatton is faster than Oscar and hattons style is a little closer to Mannys than Oscars is. I saw Mayweather KO Hatton so I see him being able to hurt Manny with a single shot like the one he landed on Hatton.