Chelsea keeping a close eye on Sinkgraven Getty

Chelsea scout Piet de Visser has admitted Heerenveen midfielder Daley Sinkgraven is on the club's list of possible targets.

Sinkgraven, 19, has also reportedly been considered by Manchester United manager Louis van Gaal following a hugely impressive season at the Abe Lenstra Stadion.

Amid the growing interest in his services, the midfielder has maintained he is not ready for a move abroad, but admits a move to Dutch champions Ajax would be his preferred destination should he leave Heerenveen.

But de Visser, the man credited with bringing Brazilian greats Romario and Ronaldo to Europe in the past, has revealed Chelsea are also keeping tabs on the teenager.

"On Daley Sinkgraven, I find it very difficult to say anything because I've agreed with Chelsea that I will not speak about the talents that are on our list," de Visser told Voetbal International.

"I follow him and that goes beyond watching a game from time to time.

"I look for five things, technique, anticipation, passing, dribbling, vision. Can he read the game, see the right solution?

"Physically, has he speed, power, endurance and mental dexterity? He absolutely has to have the will to win. And finally, how is his character? Including the family that he comes from. Is he stable?"

Heerenveen will hope to retain the services of Sinkgraven during the January transfer window but will expect a fight to hold onto the starlet in the summer.

Should he leave, Sinkgraven himself would prefer to remain in his homeland for at least another couple of years.

"I see it is a compliment that such big clubs are interested," Sinkgraven said in November.

"I would first prefer to play at the top of the Netherlands. I think it is too soon to move to a foreign country. Ajax would be a nice step."

Ajax boss Frank de Boer has also recently revealed he is hoping to sign the midfielder as soon as possible.