Gunners can take positives from moments that rocked the Catalan giants
The Gunners haven't had to look far for reminders of Lionel Messi's stunning four goals in the Camp Nou that firmly cemented his place at the top of the world game.
What can be easily overlooked, though, is that Arsenal were actually on top in the tie just moments before the Argentine took over completely.
Indeed, when Zlatan Ibrahimovic scored twice in the second half of the first leg at the Emirates, it looked like the tie was dead and buried before 60 minutes had even elapsed.
And yet the period of the tie that followed brought an astonishing turnaround...
First Leg, 69 minutes, Arsenal 1 (Walcott) Barcelona 2
Theo Walcott gave Arsenal hope after making an instant impact as a substitute. Abou Diaby won the ball from Sergio Busquets and laid it off to Cesc Fabregas. The Gunners captain then moved the ball forward to Nicklas Bendtner who fed Walcott in behind Maxwell. The England winger took one touch and shot to Victor Valdes’ right and although the Spanish keeper got a hand to the ball he could not keep it out. Arsenal could see a lifeline.
Arsene Wenger has conceded that Arsenal showed Pep Guardiola's side far too much respect in the opening 60 minutes of the game at the Emirates. They allowed the Spanish side far too much time and space on the ball and in the end they were punished.
But the introduction of Walcott added some much-needed cutting edge to Arsenal's attack and his pace frightened Barcelona. Suddenly it was Arsenal who were showing attacking intent and their midfielders were playing the England winger into the space behind the full-backs.
The goal finally came thanks to Walcott lifting everyone around the ground and a young Arsenal team were believing they could trouble the Champions League holders. After that goal, the Gunners' philosophy seemed to change and they sensed they could get something out of the game.
First Leg, 85 minutes, Arsenal 2 (Fabregas pen) Barcelona 2
Theo Walcott was involved again as his cross was diverted into the path of Nicklas Bendtner, who headed the ball down to Cesc Fabregas. The Arsenal captain was all set to pull the trigger when his leg became entangled with Carles Puyol's and he collapsed to the turf.
Referee Massimo Busacca pointed to the spot and also showed the Barca captain a red card for his part in the incident.
The Emirates Stadium held its collective breath as the Arsenal captain stepped up to take an 85th-minute penalty against his boyhood club. Fabregas held his nerve and powered home his strike past Valdes, drawing the Gunners level at 2-2.
While it only meant a draw for the home side it was a significant result because Barcelona battered Arsenal for most of the match, but the Gunners showed great strength of character to fight back. Despite conceding two away goals, it could have been much worse for Arsene Wenger's side and they had Manuel Almunia to thank for not conceding more.
It meant the tie was all square going to the Nou Camp and it gave the Arsenal players the belief that they could hurt Barcelona if they got hold of the ball.
Second Leg, 18 minutes, Barcelona 0 Arsenal 1 (Bendtner)
Aggregate: Barcelona 2 Arsenal 3
Arsenal took the lead for the first time in the tie as Abou Diaby won the ball in midfield off Gabriel Milito and played Walcott in behind the Barca defense. The England winger squared the ball to Nicklas Bendtner, who at first seemed to have wasted the opportunity, but the Dane latched on to the rebound to put Arsenal 3-2 up and in dreamland.
Not many people gave an under-strength Arsenal side a hope in hell of beating Barcelona at the Camp Nou last season. The Gunners travelled to Spain without first team players William Gallas, Alex Song, Andrey Arshavin, Robin van Persie and captain Fabregas so they were up against it right from the start.
But for 18 minutes the north London club got away with some shaky defending and then suddenly found themselves in front. The small pocket of Arsenal fans in the 100,000 seater stadium were in dreamland and thinking they were about to witness one of the greatest shocks in Champions League history.
They dared to believe and the players also picked up in confidence, and seconds later they could have made it two had Diaby noticed a unmarked Walcott on the right hand touchline. The French midfielder ignored the calls from his team-mate and lost the ball in the Barca half.
And then the wheels came off...
Arsenal were in the lead for three minutes before Messi fired in the equalizer with a snap shot on the edge of the penalty area.
It seemed the Arsenal goal angered Barcelona and in particular Messi, who sparked into life.
The players in the Gunners' shirts could not get near the Ballon d'Or winner and he went on to net all four goals for the Catalan side in the 4-1 victory, including an audacious chip when one-on-one with Almunia for his hat-trick, which took just 21 minutes to complete.
There is no doubt that over two legs Arsenal were second best and they caught Messi at his unstoppable best at the Camp Nou.
However, this time around, the Gunners will also have most of their squad available for the match. Only Bacary Sagna, who is suspended for the first leg, Diaby (calf) and Thomas Vermaelen (Achilles) will not be available for selection.
In essence, Arsenal need to have a selective memory. For 40 minutes they not only competed with arguably the best side in the world, they beat them 3-0.
Whether they can take that up-and-at-'em spirit, which is so untypical of Wenger's normal approach, and make it last over two legs remains to be seen. Unsettling Iniesta, Xavi, Messi & Co. can be done - it's making it count that's the problem.
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