Manchester United manager Sir Alex Ferguson has backed David de Gea to "realise his potential" in the next three years.

The 21-year-old has come under criticism during his first season at Old Trafford after a number of costly errors.

However, Ferguson believes that the Spaniard will grow into a better player.

"The boy has got a great talent there is no doubt about that," said the Scot. "He has made two or three mistakes coming into the game at 20 years of age, he is 21 now, but in two or three years' time we won't be discussing that at all because he will have matured. He will realise his potential then.

"It is highlighted when you make a mistake at United. It can be exaggerated a little bit. But there are mistakes and he wants to address it himself. He will do through maturity and the understanding of the English game."

De Gea is in line to start for United against Chelsea at Stamford Bridge on Sunday.