Reo-Coker was dropped from O'Neill's plans for last weekend's league game with Portsmouth after the pair had clashed at Villa's Bodymoor Heath training complex.
The 25-year-old former West Ham United player also did not feature in the midweek Carling Cup encounter with Cardiff despite O'Neill making several changes to his line-up.
After the altercation, O'Neill told the club's website: "There was a mishap on the training ground. It's a common occurrence between players but on this occasion, unfortunately, it was between the manager and a player.
"There was a bit of a contretemps and that is unfortunate. Nigel didn't train this morning and obviously won't play tomorrow. I have dealt with the issue how I see fit and that's the end of it. Come Monday, we're back to normal again. I am the custodian of this place - my rules apply."
Reo-Coker may be needed as the in-form Steve Sidwell has been ruled out with a thigh injury.