Arsene Wenger is not renowned for his tactical flexibility. The longest-serving manager in the Barclays Premier League has long lived by the “we’ll play our own game” maxim, only to be hoisted over and over again on his own petard – most notably in the countless counter-attack inspired drubbings at the hands of Alex Ferguson’s United sides over the years.

But recently, there have been signs that this particular ancien chien can learn new tricks. Recall Arsenal’s 2-0 away victory at Manchester City in January of this year. On that day, Wenger set up his side in a flat 4-5-1 shape, looking to soak up City pressure and take advantage of their well-known weakness against the fast break. Sound familiar?

Arsenal enjoyed only 35% of the possession in that City triumph – the lowest total they’d managed since Opta began paying attention. It was a clear sign that Wenger was – finally – willing to countenance planning for the opposition in his tactical preparations. This evening, his side didn’t even break 30%. And yet they were far more threatening in the final third than the ball-monopolising German champions.

Arsenal’s 4-5-1 here matched up against a Bayern 4-1-4-1, with Guardiola disappointing tactical Melvins everywhere by deciding not to opt for the bizarre rotating 3-4-3 Diamond shape that blitzed Dortmund a few weeks back.

This match-up left Xabi Alonso, Bayern’s veteran deep-lying playmaker, free in possession, with Arsenal striker Theo Walcott focusing on troubling the shoulder of the last defender rather than on picking him up. Bayern’s best two chances of the first-half stemmed from the freedom afforded to the Spaniard. The half’s top passer and chance-creator threaded the ball through for Thiago to collect between the lines, one-two with Muller, and force a fine save from the recalled Petr Cech. And Alonso was also unmarked when he set-up Vidal’s strike from the edge of the area that the skullcap-sporter dealt with equally capably.

Other than relying on Alonso threading the eye of the needle, the visitors were forced to go around Arsenal’s compact defensive unit. The exhilarating Douglas Costa hugged the touchline on the left and gave the equally speedy Hector Bellerin a torrid time. Arsenal had to rely on a number of key interceptions and clearances from Per Mertesacker to repel the danger from the resulting deliveries – and the deeper ones coming from right-back Philipp Lahm, who was often allowed to roam free by the high positioning of Alexis Sanchez.

Sanchez had Arsenal’s first of many clear-cut chances in the 7th minute, when he took advantage of Bayern’s loose shape at a defensive transition to get in between the lines and feed Ozil. Bernat dived in, allowing the German the chance to strike, but Manuel Neuer’s diving save – and a great block from Phillip Lahm off Theo Walcott’s rebound – repelled the danger.

Sanchez himself had a golden opportunity to put Arsenal ahead on the half-hour mark, shooting wide when free at the back post from a corner. Defending set-pieces was a huge issue for the visitors tonight. Manuel Neuer’s poor decision to come and claim for the first concession resulted from selecting a comically high defensive line to face Santi Cazorla’s indirect free-kick. And Giroud should have doubled Arsenal’s advantage with a free header from eight yards off an Ozil corner moments later.

Neuer’s second-half calamity followed what was a genuinely world-class save in the first. More poor defensive transitioning from Bayern resulted in Thomas Muller failing to track Nacho Monreal. The Spanish full-back’s overlap and cross found the head of Theo Walcott in the six-yard box. Somehow the sweeper-keeper clawed it out with his left-handed, Banks-esque, dive.

The second half saw much less goalmouth action for the first half-hour, with the only incident of note being a fourth hamstring injury in 12 months for Aaron Ramsey. Questions must be asked of the Arsenal medical team on that front.

Alonso’s influence on proceedings had waned by this point, with the Spaniard removed in favour of Joshua Kummich with twenty to go – along with the disappointing Vidal. Arsenal swapped the effective pace-in-behind of Theo Walcott for the hold-up play of Olivier Giroud at the same time. That change would prove crucial.

Bayern had resorted to attempting ineffectual diagonal balls in behind Nacho Monreal in the second half, which the full-back proved more than equal to – unsurprising given the continued depth of Arsenal’s defensive line. It was no surprise either, then, when Bayern’s first real clear-cut chance arrived as a result of a fast break in the 75th minute – after a misplaced pass from the otherwise solid Francis Coquelin. Muller fed Costa who fed Lewandowski in turn. But the Polish striker couldn’t add to his tally of 16 in the last 12, as Petr Cech again stood up to be counted and come to his side’s rescue.

Lewandowski had one more big chance to level the game late in injury-time, which he fashioned himself with a fantastic first-touch to bypass Koscielny. Incredibly, the most clinical centre-forward of the day hesitated and the chance passed him by.

Seconds later, Arsenal had matched that January Etihad scoreline, thanks to a Bellerin interception and cross and a fifth official-approved Ozil finish.

That completed a richly deserved victory for the Gunners and one that gives them a genuine chance again in this group. With their manager now belatedly showing a much longed-for tactical pragmatism, who knows where the glass ceiling lies for this team?