Fergie sure De Gea will be a success
De Gea, 21, has made a number of high-profile errors since joining United from Atletico Madrid for £18.9 million last summer.
Most recently, the Spaniard endured a disappointing outing against Liverpool as United slipped to a 2-1 loss versus their rivals at Anfield.
De Gea is expected to return to the starting XI this weekend, after missing out against Stoke through illness, and he is poised for an extended run in the side with Anders Lindegaard ruled out for at least four weeks with an ankle injury.
And Ferguson is certain De Gea will prove his doubters wrong, stating: "The boy has got a great talent. He has made two or three mistakes but in two or three years' time we won't be discussing that at all because he will have matured. Then he will be realising his potential.
"When you make a mistake at United, it is highlighted and can be exaggerated a little bit. They are mistakes and he wants to address it himself. He will do through maturity and the understanding of the English game.
"It is harder when you are replacing Edwin van der Sar and Peter Schmeichel. They are probably two of the greatest goalkeepers in European football over the last 40 years.
"That is not easy. I found it difficult to replace them. That's why we went for a young replacement, who would develop and mature into the position because the potential is there."