Martial has impressed in his first season as the main man up top this season, scoring 16 goals in all competitions.
But Ferdinand says: “Big clubs you've got to fight, that's it. That's all it boils down to. Can you fight for your position? That's it.
“You've got to accept there's going to be an opportunity for someone else to come in and play.
“But then your performances have got to outweigh everything. You've got to make sure the manager knows."