He said: "I think Theo Walcott can be the new Wayne Rooney but he has to change his style of play.
"He must work hard in training because everyone knows where he will run with the ball.
"He goes on his right foot - so he must work to come on the inside on his left foot.
"He must be less predictable and more focused. He can also take too long on the ball."
Asked if Walcott listens to his advice, Gallas replied: "I hope for him he does because he has great potential."
