There could have been easier tasks than knocking out the holders and arguably the best team of the modern era for Arsene Wenger, but here is why the Gunners could win the first leg.
For all the problems that Arsenal have, and all the undoubted quality that Barcelona have, it doesn't seem to make sense that the Gunners could have a chance of beating the Spanish giants.
Having Lionel Messi, Luis Suarez and Neymar - you wouldn't think the Arsenal defence will be getting much sleep the night before. Nevertheless, here's why they can tackle the tie:
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TURN UP FOR BIG HOME GAMES
Why it may seem pretty crazy to back Wenger's side over the hugely talented Barca - there is method in my madness.
It's actually not mad at all. It would, in fact, be typical Arsenal in recent years. You only have to look at this season's Champions League to see why.
Lose to Olympiakos and Dinamo Zagreb in the two opening group games, then, because of those results, given no hope against Bayern Munich.
But what happened? They beat Pep Guardiola's side 2-0. Yes, that's right. With all the defensive frailties the Gunners have and all the attacking prowess of Bayern, the north London club kept a clean sheet.
It doesn't make much sense does it? A team with Per Mertesacker in defence and Santi Cazorla at holding midfield preventing the likes of Robert Lewandowski, Douglas Costa and Thomas Muller scoring.
Once again, Arsenal are heading into this game the unequivocal underdogs. Top of the Premier League in January and now behind their arch-rivals Tottenham after picking up three points in a month.
It's very predictable of Wenger's side to drop points they're expected to win in the Champions League by getting complacent, and then go and defeat Bayern. While it's, again, predictable that they draw at home to Southampton, then turn up against Barcelona and overthrow them.
The mentality of Arsenal in the big games at home, in which they're expected to struggle, changes. While people will point to the fact that the Gunners lost at home to Chelsea and drew to Liverpool at home, those were the games they were expected to win.
Then when it comes to Bayern and Manchester City - games in which they're not expected to win, or at least find it difficult - they take the three points home.
When the pressure is on in the Champions League, Arsenal crumble. I.e. Zagreb, Olympiakos and Monaco. When it's off - Bayern at home and Barcelona at home, where they're not expected to see much of the ball, they thrive.
One reason being they're not as complacent because they know the quality of the opposition and another being they're not as susceptible to the counter-attack.
Arsenal counter-attacked Bayern themselves this season. Sat deep and relatively solid, then when the chance came they broke.
The Gunners realised, and should realise more often, that they're incredibly vulnerable to the counter-attack and have weaknesses in defence, so instead of making it easy for a European giant, they stay compact.
If they applied that to more European games then they might actually win the tournament. Unfortunately they don't and didn't apply that principle to Monaco last year.
Another way in which Arsenal can trouble Barcelona is set-pieces. The source of the first goal against Bayern for Wenger's side.
Luis Enrique's side's perhaps only weakness is set pieces and while the north London club haven't been as effective from set-pieces as last year, they're still a threat.
With one of the best players at delivering from dead-ball situations in Mesut Ozil and one of the best at connecting from them in Olivier Giroud, it's a menacing characteristic that is rarely identified by the opposition.
Guardiola, as quoted by The Daily Mail, seemed surprised by Arsenal's tactics and labelled them a "long ball" team.
"They play long ball to Olivier Giroud and if they win these balls, they can play with all the big, big, big players they have.
"But if they lose the ball and we make two or three passes, Mertesacker doesn't want to stay up high, and so they go back into their box and defend there."
It's important that they start Theo Walcott though and leave Olivier Giroud on the bench like Wenger did against Bayern.
That way Arsenal can hit Barcelona on the counter attack with Walcott's pace, then play direct to Giroud in the latter stages, to try and nick a result.
Failure to do this and the plan they executed against Bayern so well is unlikely to come off.
KEY PLAYERS HAVE RETURNED
The importance of Francis Coquelin returning is a major boost. When you're going to be looking after Suarez and Messi picking up spaces in front of the defence, they need someone to snuff out the danger.
On top of that, they need Alexis Sanchez for the counter-attack and his overall ability to win free-kicks when the Gunners are under the cosh.
While both of those are critical to Arsenal, there aren’t many players more important than Petr Cech.
If it wasn't for the former Chelsea goalkeeper they might not have defeated Bayern. One of the standout players in the Premier League this season and has solved a long-standing problem for Wenger.
In recent years Wojciech Szczesny has let the Gunners down in big moments. Palming out Daniel van Buyten's near-post header to Muller to give the Germans the crucial second away goal. Then a year later getting sent off with an hour to play.
Now they have someone who they can rely on in Cech. Barcelona aren't going to be completely nullified by Arsenal's defensive work, they will have chances like Bayern did. The Czech Republic international will likely have to be at his best again to deny Barcelona's incredible front three.
It's far from easy for Arsenal, they're underdogs for a reason. The pressure is on Barcelona but when you have the best player in the world, sometimes it doesn't matter how well you can play, he can change a match in an instance.
Not to mention, Enrique might be expecting the same counter-attacking tactics from Arsenal which Guardiola perhaps wasn't and might have a plan for it.
It's very unlikely they will go through to the next stage but recent history suggests they might be able to make the most of the home advantage.