ActionScript 3.0 :: Smooth The Keyboard Press?

I have this code to move my player...

Code:
stage.addEventListener(KeyboardEvent.KEY_DOWN,keyboardPress);
function keyboardPress (key:KeyboardEvent):void{
if (key.keyCode == Keyboard.LEFT){
player.x -= 4;
}
}

...however, when the left key is pressed, the player jumps left once, pauses, then continues to move left.

In AS2,
Code:
if (Key.isDown(Key.LEFT)){player.x -= 4;}

provided for a much smoother movement.So, what is the code equivalent in AS3 of the code from AS2 above? Or, in other words, how do I write a smooth keyboard movement code for AS3?