Cesc Fabregas’ pair of goals yesterday against Boro were presumably the kind of return Arsene Wenger has been hoping for since taking the decision to play the captain in what Arsenal fans have come to call the Bergkamp position. The link man between attack and midfield.

In one sense, it’s a new formation because Arsenal with Bergkamp and Henry were regarded as lining up in a 4-4-2. But how often did Dennis hang around in the kind of area that Cesc is playing in now? Ultimately, if you look at one of those diagrams that tell you where a player made his touches of the ball on the pitch, I suspect the Dutch maestro would be a bit further forward, but ultimately, the big change here is simply that the manager has elected to move a midfield player forward rather than ask a forward to do the same job.

So it’s 4-2-3-1 we are watching with a trio of attacking players between the target man and two screening midfield players. Samir Nasri has been converted into one of these. It will be interesting to see how he adapts to the role. He was fairly disciplined positionally yesterday and the conversation he and Cesc were having as they left the field at the end of the draw at Liverpool suggests they are both intelligent footballers who want to make the system work. Denilson was dogged yesterday, but one suspects it will be Song and Nasri that line-up against Manchester United on Wednesday.

The problem for the manager would seem to be the likelihood that Cristiano Ronaldo will be unleashed on Kieran Gibbs. I have a feeling that, with Van Persie presumably injured, Denilson might be switched to Arshavin’s current position to ensure there are two players to cover the stepover queen. We’ll see. You can’t rule out Eboue ahead of Sagna and Theo benched if the manager decides caution is the best way to go, although Arsenal’s best approach can only be to go down with all guns blazing.

You can see why Middlesbrough have scored so few goals this season. They created the kind of chances United will gobble up if presented with them, but failed to beat the keeper. They lack the clinical forward that can make the difference between mid-table obscurity and relegation. Arsenal have presented chances aplenty to opponents since the Villarreal second leg. They can use the Wembley pitch as mitigating evidence for the semi-final, but at Anfield, they were simply over-ran. At home to Boro, it looked comfortable, but Alex Ferguson, watching from the director’s box, would have taken plenty of encouragement.

One suspects Silvestre’s half-time injury was diplomatic, and that Djourou will start at Old Trafford. That can only give the defence more solidity, but if Arsenal are to remain in with a chance by the time of the second leg, the team will have to work like Trojans on Wednesday, and have an attacking mindset.

Cup games are strange things. I cannot predict what the hell will happen in the first leg. It could be one of Wenger’s finest nights, or one of his worst. A foreign ref will hopefully improve the team’s chances of fair decisions, but the experience of the Liverpool tie last season shows there is no guarantee. Anything could happen, but one thing is for sure. If Arsenal repeat some of the basic errors that have led to loss of possession seen all too frequently at Wembley and Anfield, they will be punished. Concentration is vital. Good luck boys.