“I had to pull in a player, Jonathan Greening, who had only played once or twice in the first team. He got a medal for being on the bench. That gives you an idea of the strength of the squad.
“Now I could change a whole team. We have a whole group of internationals who weren't involved on Wednesday.”
Although Sir Alex will make a number of changes for the Reading tie, he insists United won’t take anything for granted against a Royals side that has lost just once in the last seven games.
“In the FA Cup, anything can happen. You don't want to be a shock. Monday, in many people's eyes would be, 'Yes, it's Reading, we have just beaten Madrid... Monday will take care of itself'.
“Monday can't take care of itself. We have to take care of that. We must get a performance off the players that respects our opponents and also the fact the FA Cup can produce shocks. We have had them ourselves. We don't want one on Monday night.”