Trick Two of the Amazing iPhone Card Routine

This trick works great as a stand alone magic trick and even better as a follow up to the first trick in the routine "Vanisher."

You just finished the first trick of the routine “Vanisher”. The spectator is amazed but skeptical of your guile.
“But wait there is more!” You say.

Present the spectator with four cards, all face up
Ask the spectator to simply concentrate on a card.
Take the four cards and turn three of them face down.
Miraculously the card you left face up was the precise
card the spectator was concentrating on!
So elegant anyone can perform within minutes.