The outcome of what promises to be a classic Champions League final between Arsenal [Images] and Barcelona is likely to be decided in one key area at the Stade de France [Images] on Wednesday.

• Gunmen demand Champions League tickets

Barca, with their formidable strike force of Ronaldinho [Images] and Samuel Eto'o, come up against an Arsenal defence which has not been breached in 10 European matches.

Arsenal's back line has been outstanding in Europe, largely thanks to the brilliance of goalkeeper Jens Lehmann.

Manager Arsene Wenger is likely to re-format his defence because Philippe Senderos is battling for fitness while Sol Campbell and Ashley Cole have returned from injury.

Cole will take Matthieu Flamini's place at left back while Campbell will retain his place at the expense of Senderos in central defence.

Although Campbell is still regarded as the more senior player to Senderos, the young shaven-headed Swiss man-mountain has looked far better than the ageing England [Images] centre-back when he has played this season.

Arsenal will be unwise to pack their midfield as they do occasionally against teams they perceive can threaten them. They will also need to play far better than they did against Villarreal in the second leg of the semi-final in Spain.

In effect, Arsenal have to be at their absolute best for 90 minutes or else Barcelona could profit with a counter-attacking game even faster than their English rivals.

Barcelona were also too good for Chelsea, beating the English champions 3-2 on aggregate in the second round, and Chelsea have been a far better team than Arsenal this season.

FINELY BALANCED

But the match is finely balanced. Arsenal's own world class maestro, Thierry Henry [Images], could hand Arsenal the European Cup for the first time in their history.

Henry is second only to Ronaldinho as the best player in the world today and, like the Brazilian, is capable of scoring brilliant goals.

Henry could well prove to be Arsenal's match winner, but Frank Rijkaard's defence is superbly organised and Henry will need plenty of support from his team mates.

Man for man, Barca look better equipped and more experienced -- but this very fact makes Arsenal dangerous. For once there is no pressure on them.

Arsenal rarely go into any match as underdogs, but they will on Wednesday and this could allow them to play their exciting free-flowing game and batter Barca into submission.

Barca received a boost to their preparations on Monday when Argentina forward Lionel Messi [Images] was included in their squad.

The 18-year-old trained with the team on Monday but has not been given the all-clear to play by club medical staff after two months on the sidelines.

However it is expected that a decision about his inclusion in the team for the final will be made after Barcelona train at the Stade de France on Tuesday.

Messi tore a thigh muscle during the second leg of his side's Champions League knockout tie against Chelsea on March 7.

"The fact that Messi will be with us will make us stronger but we don't know if he will play in the final," Barca midfielder Deco told a news conference at the Nou Camp.

Wenger is confident Arsenal can win saying his team looked stronger than ever in the build-up to the match.

"Barcelona are the favourites," Wenger was quoted as saying by French daily l'Equipe on Monday. "But we are serious outsiders and we are determined to do our best.

"We can beat them. It's a final and you always have a chance. My team have banked on (winning) this competition and I'm certain they are going to assume their responsibilities, meaning they are going to win," he said.

Probable teams:

Arsenal: 1-Jens Lehmann; 27-Emmanuel Eboue, 28-Kolo Toure, 23-Sol Campbell, 3-Ashley Cole; 13-Alexander Hleb, 15-Cesc Fabregas, 19-Gilberto Silva, 7-Robert Pires; 9-Jose Antonio Reyes, 14-Thierry Henry.

Barcelona: 1-Victor Valdes; 2-Juliano Belletti or 23-Oleguer, 5-Carles Puyol, 4-Rafael Marquez, 12-Giovanni van Bronckhorst; 15-Edmilson, 20-Deco, 24-Andres Iniesta or 17-Mark van Bommel; 10-Ronaldinho, 8-Ludovic Giuly, 9-Samuel Eto'o.

Referee: Terje Hauge, Norway