Greenwood has lost his first-choice status in recent weeks amid claims of De Zerbi and his staff being disappointed with the player's attitude.
RMC says De Zerbi is critical of Greenwood's application given the talent and potential he possesses. OM management believe the forward needs to push himself more.
As such, there are now internal discussions about selling the former Manchester United prospect this summer.
RMC Sport journalist Florent Germain reports: "He is a player that can make a big difference but honestly, if he doesn’t react, questions will be asked about a departure for Greenwood this summer.
"If he isn’t able to understand that his manager and his directors fought against a risk – more than a sporting risk – in bringing him, to give him a visibility, because OM isn’t Getafe."