I'm rooting for Miguel Cotto 100% but my gut tells me Cotto's gonna get cut and have to fight blind in one eye and that'll allow Manny Pacquiao to win more rounds to secure a decision win. The Southpaw vs. Orthodox style always results in several head clashes.
Miguel Cotto in my opinion is the best fighter Manny Pacquiao will have fought to date and I think Cotto's body attack can really damage Pacquiao but in recent fights Cotto's body attack has been less of a factor. Pacquiao
takes a good punch and his greatest weapon to me isn't his speed and power but his stamina. The guy doesn't slow down for 12 rounds and if Cotto is hurt or cut, pretty much hampered in any way he's gonna have one hell of a time keeping Pacquiao at bay. Pacquiao has a killer instinct in there.
Pacquiao on the other hand will be dealing with a prime or close to his prime full fledged welterweight who has good defense and can box really well. Not to mention he's shown unbelievable heart in numerous fights. I think Cotto will show flashes of brilliance in this fight especially when he gets Pacquiao on the ropes. He timed Shane Mosley's speed with his jab amazingly well in that fight and if he can time Pacquaio's speed with it he'll fair very well.
All in all my prediction is a Pacquiao decision win mainly based on my first paragraph. I think there will be numerous clashes of heads given both guys styles of leaning forward when they fight and I think Cotto will be the one who gets cut open and he'll fight with a handy cap for the fight.