velocity direction

In my game, there is a ball that gets a velocity in the beginning, like this:

var velocity : float = 15;
function Start () {
	rigidbody.velocity = new Vector3(velocity, 0, 0,);	

Now the problem is, if I rotate the ball, it keeps on going along the global x axis (Even if I rotate the ball before the game starts, it just follows global x.). How can I make the ball follow its local x axis?



Use Transform.InverseTransformDirection.