He would need to throw a real hard, flush left hook to the liver to end it with one punch. He's not one punch KO guy though, never was. But he is very strong.
You just strike me as a Mosley fan clasping at straws... and if anything Shane's style plays into Manny's strengths as Mosley thows wide and is prety easy to hit... and if Mosley is really as shop worn as he appears to be then he becomes a very easy target for a man who throws straight punches in bunches like Pacquiao does. You, like most other Mosley fans, overrate his power and I don't see how he'd all of a sudden land somekind of miracle punch on a fighter like Pacquiao who's proven to have a very solid beard against several elite fighters with a good punch over several weight divisions. I mean seriously dude, if your only hope of a Shane vitory is a lucky one punch knockout then you mind as well give up because that didn't happen against Floyd and it ain't gonna happen to Manny.