Neymar was suspended from first team duty last week after an ugly blow-up with Dorival.
He was due to return to action last weekend against Corinthians, but Dorival chose to leave him out of his squad. While agreeing with the original suspension, Santos directors were angered by Dorival's decision to extend the ban and turned on their coach this week.
Just hours before his dismissal, Dorival said: "I am clear conscience. I'm not punishing him with pleasure. I do it because it's necessary."