Quite an impact: David Luiz (left) has impressed at Stamford Bridge since his ?25m move in January
DAVID CAN BE A GOLIATH
David Luiz is technically exceptional. He has the accuracy and distribution of a midfielder - he passes with such pace and it is always to the feet of an advancing team-mate. He could play the holding role very comfortably, he has defensive instinct but can link play.
There is a spirit about him, too. He looks like he wants to make things happen and is extremely confident. It's not easy to go into that changing room as a ?25million, 23-year-old defender and be expected to perform in the big games - and they don't come much bigger than Manchester United.
PLAY FAST AND LOOSE
He's susceptible to an over-eagerness to win the ball when he's facing one-on-one situations. I like the way he's dominant and the way he smothers his opponents - that's unusual as young players are naturally cautious - but he must be careful when he gets so tight.
It's refreshing to see a young defender try to dictate to strikers, but he was so intent on winning the ball back from Rooney that he was all over him. He needs to get the balance right. Luiz needs to learn to be more like Ricardo Carvalho - stealing and pinching the ball rather than steaming in.
All over him: Luiz got tight to Rooney (right) but the Brazilian must learn to nick in and steal the ball away
DON'T BE A TARGET MAN
Because he plays so tight he could start getting targeted. Clever front players will take a dive and try to buy free-kicks and penalties. He's so tight it's quite difficult to officiate because you can't tell if it's a tangle of legs or a foul. He's already been involved in a couple of incidents, but he got the benefit of the doubt.
Carlo Ancelotti swapped him to right back late on to keep him away from Rooney. If you give away a penalty or a free-kick then all that good attacking work goes out of the window.
CROSSING IS A WEAKNESS
A particular weakness is defending crosses. He tends to ball-watch, getting dragged towards the play, which allows players to wheel off him. He needs to set up right and stay on the shoulder of whoever he is marking. It's an area that will be exposed against Premier League teams who play the long ball.
It was only when defending crosses that I saw John Terry communicate with Luiz against United; perhaps he needs to give him a bit more advice.
In response to Luiz's attacking play, Terry went on the charge with the ball more often than I've seen in the past. It was as if he was trying to prove he was still the top dog.
EXPOSED BY THE SYSTEM
High five: but Luiz was not protected by Essien or Chelsea's other midfielders for Rooney's goal
People criticised him for Rooney's goal and he should have raced out quicker to deal with the danger. In a similar position late on he was lucky to escape a second yellow card when he fouled Rooney and that was because someone would have told him to close the striker down faster.
But Luiz was exposed by Chelsea's new system. He was forced to fill a little pocket in front of Chelsea's back four that never used to be there. Chelsea always used to have a player sat in front of the defenders, but now they've gone 4-4-2 or 4-3-3 they haven't got that any more and Luiz was the one who had to keep coming out. Michael Essien didn't sit deep, Ramires was forced out wide because Patrice Evra kept bursting forward and Frank Lampard was hell-bent on getting forward himself.
If ever there was a sustained period of United possession, they could tickle a ball in to Rooney and Luiz would have to burst out and deal with it while the rest of the back four would stay still, anchored on the edge of the box. The whole four should be squeezing that area as they don't have the protection they used to have.
CUT OUT THE HOWLERS
He looks as though there is a howler in him every now and then. He's just over-enthusiastic at times and miscalculates a tackle.
When he gave that penalty away at Craven Cottage on his full debut, only five minutes earlier he made a tackle in the box where he went to ground very early and almost took his opponent before he had the ball. My heart was in my mouth. It was a wild challenge and he should have learned his lesson. When you're playing against him people will try to take advantage of that.
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