It's all part and parcel of the game of football.
The manager has the right to change whomever he pleases, be it because of lack of skill, lack of determination, lack of attitude, lack of adherence to the game plan, change of game plan, or even because of a perceived slight injury.
The player has to adhere to the manager's wishes, he can fester if he wishes, but I'm sure that the player would speak with the manager, or even vice versa, at the earliest opportunity, to sort things out.
No good someone rocking the boat unnecessarily.
Players know that they are pawns in a game of football, played by two managers who try to defeat each other by any means possible. Some managers go too far, but they always have some respect for each other in the ruthless game of football.
It used to be a sport, but money intervened and it has now become big business.
Progress? - pah!!!!!!!!!