David Villa's opener looked to have given first blood to Barcelona but two very well-taken Arsenal goals see the English side take a slight advantage to Camp Nou.
David Villa opened the scoring on 26 minutes but the Gunners equalized through Robin Van Persie with 12 minutes to go. Arsenal were in dreamland on 83 minutes when Andrey Arshavin scored the goal that gives Arsene Wenger's men something to hold onto in the return fixture in three weeks time.
Arsenal had the first glimpse of goal on six minutes when Theo Walcott trickery saw the winger lay the ball off to Cesc Fabregas whose chipped pass fell to Robin Van Persie six-yards from the goal. The Dutchman smashed a powerful effort at goal but Valdes repelled the shot impressively.
Barcelona took a while to get into the game but on 15 minutes created the best chance of the game so far. David Villa's precise through ball bypassed both Arsenal centre-backs to leave Lionel Messi one-on-one with Wojciech Szczesny. The Argentinian looked odds on to score his seventh Champions League goal of the season but his six-yard chipped effort landed the wrong side of the post.
Then hosts were back on the attack in the 25th minute when the lively Walcott ran 40-yards with the ball before sliding a pass to Fabregas on the right side of the area. The former Barcelona man clipped the ball in the direction of Van Persie, but Eric Abidal's last-ditch header thwarted the striker from heading into an empty net.
However it was the Catalan who scored the opener and a vital away goal a minute later. Iniesta's precise pass found Villa with Gael Clichy playing the deadly striker onside who made no mistake in slotting the ball past Szczesny for his third Champions League goal this season.
The La Liga leaders were on the prowl again on 28 minutes and came very close to adding a deadly second. Villa showed quick feet on the right before delivering a low ball into the six-yard box. Pedro was on cue to flick an improvised backheel goalwards but Szczesny did superb to tip the ball around the post for a corner.
The game continued to be played at the predicted frenetic space and Arsene Wenger's men could have equalised a minute later. Jack Wilshere's wonderful pass found Van Persie who uncharacteristically smashed the ball high and wide into the crowd when it looked easier to test Valdes.
Barcelona had the ball in the back of the net for a second time on 38 minutes but an offside flag saw the goal ruled out. Messi's incise through ball fell to the feet of Pedro who could not beat Szczesny from 12 yards out. Messi was on hand to head the rebound into an empty net but the lineman ruled the goal out despite replays showing it to be a tight decision.
Arsenal started the second half in the lively manner they began the first and tested Valdes on 48 minutes. Wilshere played a nice one-two with Fabregas before seeing his powerful 25-yard effort comfortably saved by Valdes.
The Gunners continued to press for an equalizer and on 62 minutes came close when Samir Nasri's near-post ball looked to have found Van Persie. However a last-ditch challenge by Pique saw the ball put behind for a corner.
Barcelona continued to look dangerous on the break and should have scored a second on 67 minutes. Iniesta slid an excellent through ball to Messi yet the world player of the year could only find the side-netting from close range, a disappointing miss from the player who has been so sensational this season.
The home side needed a moment of inspiration and on 79 minutes Van Persie delivered a moment of magic. Clichy clipped in a wonderful ball to the 27-year-old striker. The angle looked too tight yet Van Persie lashed a powerful shot past Valdes and into the far corner.
Arsenal completed the turnaround on 83 minutes with supersub Andrey Arshavin scoring a well-worked second. Nasri's superb run was found by Fabregas and with Barcelona short in numbers at the back the French winger was able to cut the ball back to Arshavin who drilled the pall past the helpless Valdes.
It could have been three on 86 minutes when Wilshere picked out substitute Nicklas Bendtner who after some decent footwork forced a low stop out of the Barcelona 'keeper.
The two sides meet again in three weeks time at Camp Nou where Barcelona will be looking to overcome the one goal deficit.