As a full-back you make your opponent do what he doesn't like to do. If he likes to go down the wing, you'll cut off the room out wide and force him inside.

Show Ronaldo outside and he's got the pace to beat you; show him inside and he will still cause you problems.

Liverpool must use the full-back and midfielder - probably Javier Mascherano - in tandem. If Ronaldo does get the ball, the midfielder comes across so the space both inside and outside Ronaldo can be closed down.