It really depends on the fight itself not only the result. Pac is coming off an amazing performance against an amazing fighter himself. Also, the gap between Floyd and the rest of the pack is not as big as people make it out to be.
if he were to at least have a similar performance against calzhaghe like his win over tarver i would put him at number 2. even though i dont think it will go that way.
If he stops Calzaghe then he should be number 1. That's a big IF... I can see him winning, but ugly, verrrrrrry ugly.