He said of his former Manchester United teammate: "Yorke has done very, very well for us and he has been a big plus.
"People shouldn't underestimate how well he has done since he came to the club.
"Maybe Dwight is a potential manager himself, somewhere along the line.
"There are one or two players we are looking at (with regard to new contracts). We are monitoring the contract situation regularly, but I am not going to give out new contracts willy-nilly."