I think Marquez needs this fight even more than Pac.
Pac did beat him 3 times, one draw was a screw up with the judges cards as was proven. The 3rd fight was the closest because Pac fought differently and did to Marquez was marquez does to others, except he also landed more and was more productive.
The fourth fight was very strange, Pac controlling it, the flash knock down, and then out of nowhere, where Pac busted his nose and looked to finally be doing what everyone expected him to do, Marquez threw a hail mary that Pac walked on to.
In Marquez's head, he knows it was one of those moments in boxing, like Eubank Watson, where 1 punch literally changed the outcome 180 degrees. I think Marquez wants to win by Ko, but not be outboxed in doing so, he knows now that with his new ''nutrition''
he has power and Pac has declined, if he can put together a Pac/Marquez fight 3 performance, Pac declines further, and get the KO, then he will be able to walk away with the knowledge he finally did it the way he dreamed.
Of course he will be delighted to have the KO win, but he still knows in all 4 fights, he has been outboxed, his style means he won't deteriorate like Pac's style will, so this really is the best chance he has of giving himself what he has longed for, or he will forever hold that knowledge that he couldn't out box Pac.
I believe a rematch will go to a Pac TKO, I do believe Pac will be ruthless, but not reckless as now he has to respect Marquez's artificial power.