Obi the one man able to keep check on Barcelona's star players

Barcelona have now scored over 100 goals in La Liga alone this season and, despite being shut out by Chelsea in the first leg, the odds are that they will hit the back of the net at Stamford Bridge tomorrow night.

As much as everyone talks about the brilliance of the front three of Lionel Messi, Samuel Eto'o and Thierry Henry, it is their midfield that allows them to dominate games. It was a real problem for Chelsea in last week's match as they were totally outplayed in this department in the Nou Camp.

Yaya Toure is a great holding midfielder but it's the genius of Xavi and Andres Iniesta that makes them tick. The Chelsea midfield couldn't get near them when they had the ball and kept giving it away when they did get possession.

Firstly, they will not start with the same 4-4-2 formation as they did on Saturday against Fulham where the midfield was so lopsided with Frank Lampard starting on the right but coming inside far too much.

In that position he's not properly utilised going forward and, defensively, he wasn't helping out his right-back, something which will have to be done tomorrow.

Michael Essien was used on the right flank in Spain last week but was only on the periphery of the game on that occasion.

Expect Guus Hiddink to revert to his favoured 4-3-3 formation with Lampard and Essien in their prefered roles pushing forward to join the attack.

Hiddink was right to use Essien as the holding midfielder against Steven Gerrard in the last round but he should resist the temptation to use the Ghanian there again.

That role should be filled by either John Obi Mikel or Michael Ballack. The German may have the greater experience but has not had a great season and should be the one left out on this occasion. Mikel is better in his specialised position than Ballack is and if the Nigerian is getting overrun, Essien can always play as the second holding midfielder leaving Lampard to support the front three.

It is vital for Chelsea to win this midfield battle if they are to feed Didier Drogba in attack.

On his day there is no better lone striker in the world than the Ivorian and he's already admitted that he feels as happy under Hiddink as he was under Jose Mourinho.

Without doubt, Barcelona's main weakness is at the back with Carles Puyol suspended and Rafael Marquez injured. Gerard Pique will be their main centre-half and he couldn't get a game at Manchester United. He's obviously had a good season but Sir Alex Ferguson rarely makes a mistake in letting players go.

Drogba will bully Pique and will be supported from wide positions by the reborn Florent Malouda and Nicolas Anelka.

The other selection issue for Hiddink to address is who plays at right-back? Jose Bosingwa has filled the role for most of the season and is undoubtedly better going forward than Branislav Ivanovic. But Henry, if fit, will be desperate to carry on the superb form he is in, especially on his first visit back to the capital since his move to Spain.

I would go for Ivanovic and use Bosingwa only if Chelsea were needing to chase the game.

Ashley Cole will also play even though Bosingwa did a great job on Messi and there's an argument for playing a right-footed left-back against the Argentine. But Cole (left) is at his best when up against a world-class winger. So, can Chelsea progress to their second Champions League Final in a row? Yes, they can but only if they keep it tight at the back, do not allow the Barcelona midfield any time on the ball and make the most of their set-pieces against a suspect Spanish defence.

Chelsea are more than capable of scoring two against the Catalan side as they have shown in the past. The criticism aimed at the Blues after last week's game was unfair. I don't believe they set out to defend, they were forced into the tactic because Barcelona were so good on the night.

Don't be surprised if Chelsea go for it and try and to blitz Barca in the opening 20 minutes and make the most of their home advantage.

It will be tight, but if Hiddink gets his team selection right, Chelsea can pull off one of the biggest results in their history against the best attacking team in the world.