Hopkins IMO is far the tougher fight for Joe. Styles makes fights, and Hopkins is a natural counter puncher which I believe is the way to be effective against him. Roy used to be a good counter puncher too, but he depended on his reflexes to deliver them in the day.

Roy did look impressive aginst Tito, but Tito was there to make him look impressive. It was touch and go the first few rounds until Tito got gunshy and allow Jones time to set himself and throw single powerful shots. While I think Roy still has pop in his punches, he needs more time to set himself up to throw them, and time is one thing he will not have against Calzaghe, as well as a breather.