In the first half, Arsenal started well and created, but failed to convert, a couple of decent scoring chances. Barca gradually played themselves into the game, then dominated for the bulk of the first half. They created more and better scoring chances, cutting open the center of Arsenal's defense (and the dangerously high offside line the Gunners' defense was playing) on a few occasions. David Villa scored on one of those chances. Lionel Messi should have scored on at least one other. The halftime score could well have been 2-0, 3-0, or 2-1. As it happened, Barca's lead at the half was a slender 1-0.
The second half was a completely different story; Arsenal dominated it from the first kick to the final whistle. I don't know what Arsene Wenger said to the team at halftime, but the entire team seemed to elevate their games in the second half, playing with more brio and self-confidence. They attacked in waves and seemed to surprise a Barcelona squad that was unable to raise its game response. However, Arsenal couldn't not break down Barca's defense until the 78th minute, when Robin van Persie smashed a shot from a severe angle, squeezing the ball between goalie Victor Valdes and the near post. Valdes probably should have had the shot covered, but Arsenal sub Nicklas Bendtner was lurking in the middle, and Valdes was caught cheating to cover the square ball.
Van Persie's goal sent Arsenal's confidence soaring even higher, and it wasn't long before they struck again, this time on a beautiful sweeping move featuring a particularly fine cut-back pass from Samir Nasri to Andrei Arshavin, who did not take a touch before shooting low past two defenders well beyond the reach of Valdes. It was a difficult shot but the little Russian made it look easy as pie.
All in all, a tremendous team performance from the Gunners, which must raise their confidence level for all competitions. Particularly noteworthy were the stand-out performances by young Jack Wilshire, who played inspired football in midfield, and Laurent Koscielny, playing his first game ever in the Champion's League, and playing with the poise, self-belief, and strength of a world-class central defender.
Much work remains to be done before Arsenal book a trip to the quarter finals in the Champion's League. They have to wait nearly three weeks before playing the return leg at the Nou Camp. Meanwhile, Barca will take consolation in their valuable away goal. But whatever happens in that match, the Gunners will have gained much from today's super victory.