Dirrell by wide decision would be my pick. Pavlik didn't look very good when he fought at 166 in the Taylor rematch. When he makes the permanent move to 168, he's going to be facing better fighters and he won't have the size/strength advantage he enjoys at Middleweight. Pavlik isn't the quickest fighter and he's somewhat flat-footed. It's easy for me to imagine Dirrell boxing circles round him. His huge advantage in speed (of foot and hand) along with his combination punching, would be a nightmare for Pavlik. I think Dirrell makes Pavlik look plodding and one-paced en-route to a convincing points win.
Dirrell UD. Maybe even a TKO later on. Dirrell has speed and with Pavlik fighting at 168, he could very well be stopped.
The fight would get so bad that Bob Arum would try to storm the ring with a baseball bat in order to protecct Pavlik
Dirrell is just as slick as Martinez, is a natural SMW, and can switch hit. Dirrell schools Pav. Dunno if Dirrell is as tough as Sergio heart wise though.