Look for the player isn't working

I was watching this official tutorial on Unity: Live Training: Top Down 2D Games - YouTube

I wish that instead of looking for the mouse he looked to the Player. So I put “public transform player;” and in FixedUpdate in place of “Input.mousePosition” I put “player.position”. But it does not work.

The complete code is:

public Transform player;

	void FixedUpdate(){

		var mousePosition = Camera.main.ScreenToWorldPoint(player.position);
		Quaternion rot = Quaternion.LookRotation(transform.position - mousePosition, Vector3.forward);
		transform.rotation = rot;
		transform.eulerAngles = new Vector3(0, 0, transform.eulerAngles.z);
		rigidbody2D.angularVelocity = 0;

	}

I’m sorry for bad English. Help me please?

Input.mousePosition is in screen coordinates and must be converted to world coordinates. ‘player’ is already in world coordinates. So delete line 5, and replace ‘mousePosition’ by ‘player.position’.