Koeman praises de Jong
The defender is a product of the famous Ajax youth academy, and signed a three-year deal last summer at the age of 16.
He has fought his way into the first-team picture this term and replaced the suspended Cristian Chivu for the win over Willem II on Sunday.
De Jong was given the nod ahead of established figures Petri Pasanen and Abubakari Yakubu, and produced a solid display in the 3-0 win.
Koeman could hardly contain his delight after the game, hinting that a new bumper deal is in the pipeline, telling the club`s website: "We will talk with Nigel in December.
"I find it amazing how mature he is playing. He has great qualities, hardly makes mistakes and is very aggressive in tackles.
"He deserves a major boost and as such I will keep him with the A-squad.
"When a player is developing like this, it is not good for him to step back again."
