Ajax boss Koeman will get a chance to assess Ferdinand's abilities on Friday when his side host Manchester United on the opening night of the Amsterdam Tournament.

Koeman, one of the greatest defenders of his generation, feels Ferdinand is already a hugely-talented player but warns there is still plenty of hard work ahead.

He said: "I think he will prove to be a good buy. You can't look at the price tag anymore than you would look at Zinedine Zidane's.

"Manchester United wanted him and they had the money to buy him. Now it's about how he performs.

"Ferdinand showed in the World Cup that he is a very good defender but the pressure on him now will be different than when he was at Leeds.

"Now he has to show that kind of quality in every game and that can be tough."

Ferdinand, along with the rest of United's England World Cup quintet, flew into Amsterdam on Thursday after missing the start of the club's 10-day trip because of their late return to pre-season training.

None is expected to play more than 45 minutes against Ajax, although a full game is likely against Parma on Sunday.