By Richard Clarke in Barcelona

It is traditional for Arsenal to start their season against Barnet in July. It is also becoming customary for them to measure its success about now against Barcelona.

Underhill and the Nou Camp do not have too much in common. Barnet are 91st in the ladder of English football while the Spanish champions are trying to resume their position on Europe’s top rung.

The game against Paul Fairclough’s men is a run-out; a gentle introduction to match-fitness in the first few weeks of pre-season.

The game at Barcelona is pretty much pinnacle of the sport. Football does not get more glamorous, more prestigious or more difficult than this.

So it was a measure of Arsène Wenger’s buoyant mood that he mentioned them in the same breath before his side left for Spain on the eve of this massive Champions League Knockout Round second leg.

"I'm not worried,” smiled Wenger. “I'm confident.

“We are playing against the best team in the world so you can't say you go there like we go to a pre-season friendly at Barnet.

"We still think we have a good chance if we play at your best. And that's what we’ll try to focus on.”

For some time the Frenchman has said that his team are ready for lift-off. Well, the countdown can begin if they make their 2-1 first-leg advantage tell in the Nou Camp. Undoubtedly this is the biggest game of Arsenal's season so far. And, though shorn some key players, Wenger has concrete cause for optimism.

A year ago, they were blighted by injuries and Lionel Messi ran riot in the final hour. In addition, Wenger lamented a crucial offside that, he argues, would have allowed Nicklas Bendtner to put his side 2-1 ahead just before the interval.

It was marginal but then everything is at this time in the campaign. Arsenal have neither the will nor the capacity to ‘park the bus’ and bolt down a 0-0 this time. ‘Careful offense’ seemed to be Wenger’s gameplan when he spoke to the media but you also sense that a bubble had been burst by that two-goal comeback at Emirates Stadium three weeks ago. Unlike last season, Barcelona will face a side steeled with the belief that they can get the required result.

"Confidence is very important I feel,” said Wenger. “We have been a bit frustrated lately by what happened in the Carling Cup and the Premier League but overall I believe this is a game in special circumstances.

"They are like us, they like to attack and defend high up the pitch so for us it's important to get through their first pressing and then I believe we have a chance. The second goal we scored against Barca in the first leg shows that quite well. The problem we face is to get out of their pressure and to try to hurt them. We can score goals, they can score goals and basically everybody expects both teams to have a go."

Cesc Fabregas passed a fitness test on Monday morning and returns to the squad after limping off with a hamstring injury two weeks ago against Stoke. Jack Wilshere was a minor doubt after receiving a few kicks on his ankle against Sunderland but has recovered. Robin van Persie's inclusion in the travelling squad was a major surprise given his knee problem was expected to keep him out a further two or three weeks. However he faced another test on the morning of the game and is far from certain to be involved. Arsenal have brought out 19 players so, should the Dutchman fail, he can be left out of the squad entirely.

Theo Walcott (ankle) is certainly out along with Alex Song (knee). Denilson or Abou Diaby are in line to deputise for the latter.

Wenger said one of Marouane Chamakh or Bendtner would start up front with the Moroccan seemingly a slight favourite.

That may be a key decision as Barcelona are without their two first-choice centre-backs – Carles Puyol (knee) and Gerard Pique (suspended). Eric Abidal, normally a left back, and Sergio Busquets, a defensive midfielder, may act as cover.

In both first legs, this year and last, Barcelona were excellent early on but tired in the second half and conceded a brace of crucial, late goals.

On each occasion, Arsenal's game forced them to chase the ball at Premier League pace. For example three weeks ago at Emirates Stadium, the Spanish champions ran 72.5 miles as a team. Around 3.5 miles more than their average in the Champions League.

In this fixture last season, Wenger’s men could not force the hosts into that deeper water. It was they who were chasing the game in the second half. This time, however, they will go in with the back four that has made them title-chasers. Not that the visitors will play a shackling game.

“A year ago I didn't even know if Sol Campbell would play until 3pm or 4pm. In the end I decided not to play him because he was tired and we played with two left-footed players in central defence which was not ideal. I believe we are better equipped defensively this time.

"But anyway is it realistic to go there and play a 0-0 from the first minute on? I believe it would be against our nature. Tactically I don't think it's defendable. We don't have a team of 11 defenders who are just happy to defend.

"If you look at their performances, they drop a little bit in the second half but physically they are a lot stronger than people expect. To play the kind of football they play you need to move a lot and that takes a lot of energy.

"And if you look at their distances, their mileage is quite impressive."

But the manager’s final words summed up his position most accurately.

"We have to realise it's a special game,” concluded Wenger. “But in a special game you don't have to be exceptional you just have to do your job.

“Only then can you become exceptional.”

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 8 Mar 2011