(CNN) For 70 minutes the plan had worked perfectly.
Barcelona, unbeaten in 32 consecutive games and with the best attacking trio on the planet, had been frustrated at every turn.
Arsenal, so often guilty of gifting its opponents goals at the last 16 stage of the Champions League in previous years, had defended with all its might.
It made what must have felt like hundreds of tackles, given everything in its locker and yet within the blink of an eye all of its hard work was undone by that Barcelona brilliance which makes football so wonderful to watch.
As Arsenal were caught up the field, perhaps seduced by the ridiculous notion it could yet somehow win this tie, Barcelona struck.
A rapid counter attack which ripped straight through the heart of the Arsenal defense concluded with Lionel Messi applying the finishing touch.
The same man then added further gloss from the penalty spot after he had been upended by Mathieu Flamini's clumsy challenge.
Two away goals and a 33rd consecutive game without defeat leaves Barcelona perfectly poised to progress to the quarterfinal stage after this 2-0 first leg win.
The margin of victory could have been greater had Luis Suarez not hit the post when clear on goal, but such failures will not worry Luis Enrique, the manager of Barcelona.
He can now surely look forward to the last eight and the opportunity to ensure his team become the first to retain the Champions League title since the competition was revamped.
All the hype before the contest had surrounded Barcelona's incredible front three -- Messi, Suarez and Neymar -- or as they've been nicknamed, MSN.
Going into this game, the three had amassed 91 goals between them this season -- that's 30 more than the entire Arsenal team.
But the trio were largely contained in the first half and it was Arsenal which should have moved ahead early in the contest.
A neat counter attack ripped through the Barcelona defense with Mesut Ozil finding Hector Bellerin but when the Spaniard's shot was blocked, Alex Oxlade-Chamberlain could only fire the loose ball into the body of Marc-Andre ter Stegen, the Barcelona goalkeeper.
Barcelona, despite dominating possession, struggled to find any rhythm as Arsenal stuck to its task of frustrating its opponent at every opportunity.
It was not until the final seconds of the half that Barcelona found a way through the home side's defense but Suarez headed wastefully wide when well placed.
After a frustrating opening 45 minutes, Barcelona began the second half on the front foot.
Neymar, who had been a peripheral figure, was denied by Cech after running onto a through pass by Andres Iniesta as the game moved from end to end.
Olivier Giroud, the Arsenal striker, had his header well saved by ter Stegen while Suarez fired wide at the other end as both teams moved through the gears.
Arsenal, beaten at this stage last year by Monaco, were beginning to believe that it could pull off the impossible.
No team had beaten Barcelona since October when Sevilla edged out Enrique's men in La Liga.
But just as the home side started to believe, Barcelona struck -- and did so to devastating effect.
A three man move including Neymar and Suarez dissected the Arsenal defense and Messi was the grateful recipient, firing the ball past Cech from close-range.
Shocked by its concession, Arsenal nearly fell further behind when Suarez hit the post after Neymar's effort had been blocked.
Arsenal was beginning to rock and it came as little surprise when Barcelona doubled its advantage with seven minutes remaining.
An awful error by Per Mertesacker inside the penalty area presented Messi with the opportunity to take possession but the Argentine was sent tumbling to the ground illegally by Flamini.
Messi, who had failed to score against Cech in his six previous encounters against the goalkeeper, kept his nerve to score from the penalty spot.
It leaves Arsenal with an uphill task to progress -- and few if any will give Arsene Wenger's side a chance in the return leg at Camp Nou on March 16.
"Barcelona is a great team," Wenger told BT Sport. "We put a lot of energy in the game and technically we were very average.
"The regret I had was once we looked like we dominate the game, we gave the goal away.
"Similar to Monaco last season, naive, and that is frustrating. When we looked like we could win the game, we just gave it away.
"Realistically it is very, very difficult, if not impossible. We have to go there and fight. We had the chances, we didn't score."
Juventus came from two goals down to draw 2-2 with Bayern Munich in Turin.
Thomas Muller and Arjen Robben had given the visitors a two-goal lead as Pep Guardiola's men took control.
Juventus, which reached the final last season where it was beaten by Barcelona, fought back with Paulo Dybala and Stefano Sturaro on target.
The two teams will meet in Munich on March 16 to decide which team makes it through to the last eight.