Ferdinand told BT Sport that Lacazette must make an impression on manager Arsene Wenger and prove his worth if he is to retain his place in the team.
"It's down to Lacazatte to say 'I'm here to fight, play me or Aubameyang - I'm worth my weight in gold'," the former centre-back said. "He scored goals in France, he's a good finisher.
"I don't who you are, what level you're at, if confidence goes out of your game you're not the same player."
Lacazette could feature for Wenger's team, who play Ostersunds in the Europa League in their next game.