Ferguson insists De Gea was not to blame for their draw at Tottenham.
De Gea had made a number of excellent saves at White Hart Lane but his weak injury-time punch gifted Tottenham an equaliser in the 1-1 draw.
Ferguson said: "He had a fantastic game. I remember talking about how well he played and then, 30 seconds from time, the ball park changes. Outfield players maybe make 20 mistakes in a game. But keepers are in a crucial position. We are OK with him.
"It is unfortunate for the lad but he has to deal with it. We will help him. I think we are quite good at that."