Barcelona must not be overconfident like they were against Chelsea four years ago when they lost the second leg 4-2 after winning the first match 2-1. I don't think it will happen because Pep Guardiola is a very smart manager and will keep his players focused.

Barcelona will probably attack from the start as usual but they must ensure they are not careless at the back. They mustn't concede too many free-kicks or corners and the two centre-backs will need to concentrate. With Rafael Marquez and Carles Puyol missing, I expect Martin Caceres to play alongside Gerard Pique at centre-half rather than Eric Abidal moving from left back or Yaya Toure from central midfield.

Barcelona are playing the best football I have seen and I can't see them not scoring. I'm expecting a match full of goals but the most crucial thing will be who scores first. If Chelsea do, it will be very difficult for
Barcelona but then everyone should remember what happened against Liverpool in the last round when Chelsea were leading 3-1 from the first leg.

Chelsea conceded four against Liverpool and they also let in three against Bolton recently, which suggests that they're not that strong at the back if they try to go forward.

A lot has been said about how strong their defence is but it is easier to defend if you have 10 players behind the ball and the priority is to stop the other team from scoring.

The midfield of Barcelona is the key. Their three attacking players are fantastic and they look so good because of the passes Xavi and Andres Iniesta are providing and the holding job Toure is doing.

If Henry isn't fit, Iniesta will probably move to the left wing with Seydou Keita coming into midfield but that won't weaken them too much. It will be more of a blow to Henry than to Barcelona as he's desperate to play Champions League matches, especially on his return to London.

I saw that Chelsea played a 4-4-2 against Fulham on Saturday but I would be happy if they just try to come out and play good football. I don't expect them to commit suicide but I hope they don't park the bus in front of their own goal and look for Didier Drogba to score on the break. If this is the case it's good for them but bad for the game.

If it is an open game, both sides will score goals but I think Barcelona will go through to the final.