Manchester United v Real Madrid: Old Trafford side must starve Cristiano Ronaldo of ball by cutting off supply lines Turn him around The first job of any defender is to identify an opposing player's weakness and then seek to force him to play on them. That is easier said than done with Ronaldo. When United played Tottenham recently, they doubled up on Gareth Bale and kept him off his left side as much as possible and the tactic worked, with the Spurs player making little impact. Ronaldo, like Bale, is a world-beater, but his weaknesses are not really weaknesses. Yes, he prefers to shoot with his right foot, but his left foot can still destroy you. He has also proved time and time again that his mental strength is as impressive as his physical strength, so he cannot be bullied out of a game. The only way to reduce the threat posed by Ronaldo is to make him face his own goal, get tight to him before he receives the ball and ensure that when he gets the ball, it is with his back to the goal you are defending. Squeeze space It will be much more difficult to defend against Ronaldo at Old Trafford than in the Bernabéu because, as the home team, United will not be able to sit behind the ball as they did in Madrid. The crowd will not let them. So United have to balance out the need to attack with the necessity to be tight at the back and that is why it is crucial that Ferguson goes with the experience of Nemanja Vidic and Rio Ferdinand at centre-half. They will know the importance of minimising the gap between the midfield and back four and are the best-equipped of Ferguson's defenders to ensure it remains tight and narrow. If the midfield line pushes forward, the back-line has to go with it. If the gap becomes too big, you invite Ronaldo to exploit the space in between and run at goal before shooting from distance, when he can be deadly. Bale showed what can happen when the gap between the two lines is too big when he scored against United at Old Trafford earlier this season. Ronaldo and Real are just as capable of capitalising on similar opportunities. Cut out crosses When he scored Real Madrid's equaliser in the Bernabéu with a stunning header from Angel di María's cross, Ronaldo reminded everybody of his incredible ability in the air. Neither of United's full-backs - Rafael da Silva and Patrice Evra - are strong in the air and Ronaldo took advantage of this by out-jumping Evra to score, but even Ferdinand and Vidic would have been unable to stop Ronaldo scoring that goal. The key to minimising his aerial threat is to stop him getting the ball in the first place. United simply have to cut off the supply and this is all about concentration and discipline. The full-backs and wide midfielders cannot afford to let Real have the opportunity to deliver easy crosses, so Rafael and Evra, in particular, have to ensure that Di María, Mesut Ozil and Real's advancing full-backs are not given the time to deliver the ball into the penalty area. Protect Rafael Ronaldo will roam across the pitch all night, but he will also target what he perceives to be any United weak spots. The first half in the Bernabéu highlighted the frailties that Rafael has yet to overcome at the highest level. When you watch the young Brazilian, you always feel that there is a mistake in there somewhere. He has improved since he allowed his naivety to get him sent off against Bayern Munich three years ago, but he is still rash, impatient and impetuous. In the Bernabéu, he had a really tough half-hour, during which Ronaldo, Ozil and Di María tormented him. If the same happens tomorrow and Ronaldo begins to target Rafael, it will be up to Ferdinand and Vidic to talk to guide him through the storm by relaying their experience. The positive for United is that Rafael steadied himself in Madrid after his bad start and showed the growing signs of maturity that have been evident in his game this season. He was terrific against Queens Park Rangers last week, but Real Madrid and Ronaldo will be a different challenge entirely and he will be under the microscope tomorrow.