Arsenal were left counting the cost of missed chances as a second-half double from Lionel Messi handed Barcelona a likely fatal first-leg advantage.
Barcelona's Argentinian forward Lionel Messi celebrates scoring his team's second goal from the penalty spot during the UEFA Champions League round of 16 1st leg football match between Arsenal and Barcelona at the Emirates Stadium in London. Pic/AFP
The hosts were the better side in the first period, and had the better chances and only shot on target before the break as Alex Oxlade-Chamberlain shot weakly at Marc-Andre Ter Stegen when presented with a glorious opportunity from six yards.
Having sat deep and cut off Barcelona's supply lines, Arsenal threatened on the counter but, unable to break the deadlock, allowed their visitors back into the game during the second period.
While Barca's glittering frontline were subdued in the first 45, they flew out of the blocks after choice words from Luis Enrique and punished Arsenal's profligacy with a blistering counter-attack that was finished by Lionel Messi.
The Argentine then won and netted a late penalty to double Barca's away goals tally and likely settle this tie. But what did we learn? Ed Malyon was at the Emirates... In the end there was no rotation.
There was no adapting for Arsenal's own threats, but just as importantly there were no injuries. It all meant that Barcelona could put out a stellar XI, the same that beat Juventus in last summer's Champions League final, to take the Gunners on in their own backyard.
While the Blaugrana have travelled much in recent weeks and not necessarily played as they can in their two most recent matches, against Sporting Gijón and Las Palmas, the biggest stage is where the biggest players are the most motivated.
Arsenal, for their part, went with their premier back four, a midfield as strong as it could be in Santi Cazorla's absence and Alex Oxlade-Chamberlain getting the nod on the right ahead of Theo Walcott or Danny Welbeck. The Ox would go off injured just after the break, but Walcott replaced him in what was a like-for-like switch to maintain Arsenal's counter-attacking threat - more on that later...
La Liga sides have got the most joy against Barcelona this season by pressuring their defenders in possession and hurrying them into mistakes. Malaga did it very successfully but couldn't take the resultant chances, while Atletico Madrid had a lot of joy doing so at the Nou Camp only to throw away their lead and end the game with nine men.
Wenger's plan for this one was, as it has been in most of their bigger games this season, to play a deep line and get everyone behind the ball. Coiled like a spring, they would then counter with pace and verve, and this strategy helped the hosts get the better of the opening exchanges - even creating a terrific chance inside fifteen minutes as Aaron Ramsey fluffed from a dangerous cutback.
Whether Barcelona's tough travelling schedule had sapped them of some of their verve and spark or they are simply doing what they've been doing all season - improving after the break - it was Arsenal who were making the running in the first half. Barca were allowed to have possession but, when presented with 11 red shirts, found themselves deprived of the passing avenues to feed their stellar front three.
Sergio Busquets did, at times, drop in alongside Gerard Pique and Javier Mascherano to form a back three and try to create, yet it felt as if the visitors were going to need a moment of magic to sneak through the compressed Arsenal lines.
When the hosts got the ball they went vertical, hitting Barca in the transition and driving at pace towards goal. It unnerved their guests and caused problems, allowing Ramsey, Oxlade-Chamberlain and Giroud reasonable chances.
But you cannot "pardon" (to use the Spanish phrase) a treble-winning side and when Barcelona did roar into action there was an ominous feel about proceedings. Arsenal knew that they would need to take advantage of their good periods but, despite besting the European champions in the first half, they failed to convert that superiority. There are far deeper numbers that prove how much Luis Enrique's side are better after the break, but here's a simple one.
They are nine points clear of Real Madrid in La Liga yet, had every game finished at half time, they'd be six points back. That enormous 15-point swing was perfectly demonstrated 10 days ago when they went into half-time level with Celta Vigo only to stick five past them in an utterly scintillating second-half performance that ranks up there with some of the best football they've played under Enrique. The goal was coming. The Arsenal heartbreak was inevitable. And just as inevitable was who scored it...Luis Enrique (unsurprisingly) thinks it. Most of Barcelona think it.
But even after less than scintillating display at the Emirates, Barcelona's glittering attack came up big to strengthen their case that they are the greatest front three to play the game. "From Barcelona, yes, it's the best of all time," Enrique said in December." And I would dare to say the best in the history of football.
"In a moment where the game was in the balance, Neymar then Suarez then Neymar then Messi combined to break the deadlock. Everything about the goal; the magical chemistry for Neymar to time that pass so perfectly, Messi's pause to send Cech to the floor, the weight of Suarez's through ball; spoke to why this trio are so great, not to mention the fact it was their 92nd goal of the season - and we're only in mid-February.