It mirrored Tuesday night in Manchester. How one ill-judged decision made in a split second can dramatically transform the dynamics of a game which was tight up until that point. It was a similar script in North London as Wenger was left incorrectly bemoaning Wojciech Szczesny's red card.
It was an evening of regrets for the Gunners as Mesut Ozil missed an apathetic early penalty and Wojciech Szczesny saw red with Bayern's David Alaba also wasteful from the resulting spot-kick.
The Polish keeper had caught Arjen Robben as the Dutchman flicked the ball past him and was all set to slot home into an empty net. It was, in truth, a deserved expulsion as Nicolla Rizzoli pointed to the spot.
But Bayern were excellent throughout, their domination increased following Szczesny's departure. It was a world-class performance from Pep Guardiola's side as they ran Arsenal ragged with their slick and immaculate passing. Arjen Robben was fantastic as he ignored the jeers of the Emirates faithful to put in a commendable display. Toni Kroos was magnificent as he played the role of composer in Bayern's rhymetic handling of the ball., with Manchester United boss David Moyes watching intently. It was the perfect away performance from the Bavarians, with Kroos's sensational strike and Muller's composed diving header providing Bayern with a cushion when the Gunners travel to Munich.
But Arsenal too deserve the plaudits. They were wonderful in the first period, posing their German opponents all kinds of problems with the pace and energy of the young side selected by Arsene Wenger, which included 21 year-old forward Yaya Sanago, who was making his Champions League debut in a significant game as such. It was a gamble, to say the least. Per Mertesacker and Laurent Koscienly were brilliant throughout with their respective gallant displays and desire to keep going. Belief was the recurring theme of Wenger's press conference on Tuesday, and his players certainly had their fair share of that.
The Gunners now have it all to do in Munich, a prospect which is no stranger to Wenger's men considering their unanticipated 2-0 victory at the Allianz Arena last season.
The French manager had reiterated the belief and determination his team possessed. He had claimed that his players were in a refined mental state, having lost against Blackburn in the FA Cup ahead of last season's fixture but experiencing victory over Liverpool this time, coincidentally, in the cup once again. And who could have disagreed with him, with his side doing well in the cup and mounting a title challenge in the Premier League. Hoping his men would channel their confidence into the match, Wenger had promised a fast start. And that is exactly what he oversaw.
The Londoners were bright during the opening fifteen minutes, but Kroos was unlucky to score against the run of play. With only three minutes on the clock, Szczesny saved excellently from the German midfielder as his powerful swerving strike was indisputably destined for the top-corner.
It was then the turn of Neuer to produce a world-class save as he rapidly fell to the floor in an amazing reaction stop to thwart Sanogo's low effort. The young French forward had made a good start to life at the elite level, having been signed from France's Ligue 2.
With nine minutes played, Arsenal were duly rewarded for their determined efforts as Nicola Rizzoli pointed to the spot. It was the correct decision from the experienced Italian referee after Jerome Boateng had clumsily tripped fellow countryman Ozil.
But then the penalty which followed deflated the optimistic hope which harboured around the Emirates. Missing regular takers Mikel Arteta due to suspension and with Olivier Giroud on the bench, Ozil grabbed the ball and placed it on the white spot.
It was a languid effort, almost arrogant, as he attempted to outwit his childhood pal Neuer. But it was his international colleague who came out on top, palming the ball over much to the frustration of the ardent Arsenal support. It would prove to be a pivotal moment in the game, and one which the Gunners will surely rue.
Bayern grew into the game and began to enjoy a considerable amount of possession with Arsenal's early pressure having fizzled out. Flamini blocked Alaba's goal-bound drive well before neat footwork from Sanago sent Chamberlain breathing down the neck of Bayern's Austrian full-back, forcing the alert Neuer to clear the emerging danger.tWenger was forced into an early substitution with Kieran Gibbs succumbing to injury and Nacho Monreal introduced as his replacement. It was the beginning of the adversities which followed for the hosts and Monreal, who was tasked with managing Robben and Phillip Lahm on the right side of the pitch.
Bayern began to assert their authority as they meticulously searched for that incisive pass to slice open the stout Arsenal resistance. And it arrived towards the consummation of the first forty-five as the outstanding Kroos lofted the ball into Robben's path. The Dutchman flicked the ball past the on-rushing Szczesny and was later clattered by the Arsenal 'keeper with a mis-timed intervention. Wenger may claim the former Chelsea winger exaggerated the impact of the collision, but it was the equitable decision from Rizzoli as he awarded a second penalty in forty minutes and delivered Szczesny with his marching orders, who made a gesture similar to the rolling of a dice.
Lukasz Fabianski replaced his fellow countryman and took his place in the Gunners goal at the expense of the dismayed Santi Cazorla. Alaba, a regular spot-kick converter at the Bundesliga champions, sent Fabianski the wrong direction but his effort kissed the post and outtt. The Emirates roared. But it would prove to be a short-term let-off for Arsenal as Bayern swapped dominance for supremacy in the second period.
But Guardiola, a known perfectionist, was not pleased yet. He made a half-time substitution with Rafinha replacing former Man City defender Boateng, who had struggled in the opening period to contend with the pace Arsenal competed with.
It was spirited display from the London outfit as they defended in an attempt to preserve their chances in Munich, and a 0-1 loss is combatable. Laurent Koscienly was absolutely fantastic as his desire to win an aerial battle, cover considerable ground and win his side a free-kick against the odds epitomized what was a gallant showing from Wenger's men as Bayern were supreme in possession.
Arsenal's only respite arrived courtesy of free-kicks awarded in their favour. Other than that, they were caged in their own-half, with Sanago dropping extensively deep to make up for their numerical disadvantage. Any errors in the Germans' slick passing was inexistent as they rapidly moved the ball side to side with a few threatening potshots included.
But the Arsenal resistance was expectedly broken as Toni Kroos curled a sensational strike into the top corner nine minutes after the interval.
The Germany international had scored a belter here at the Emirates in the previous season as he once again played a pivotal role in Bayern's convincing vital victory.
Guardiola stood on the touchline in an agitated manner, displeased with his side's ineptitude to score a second away goal and from his perspective, put the tie to bed.
But his men proceeded in waves of sustained attacks and came close to netting their second. Robben, who was comprehensively tying Monreal into knots, ran past the Spaniard who was totally oblivious to his clever run and his effort, a mix between a cross for Mandzukic and a shot a goal, was thwarted well by Fabianski, who had been in front line action on Sunday in what was a strong performance to conserve Arsenal's existence in the FA Cup.
In a show of strength, Thomas Muller came on for Mario Mandzukic as Guardiola ceased to capitalize on Arsenal's numerical misery to boast a convincing advantage ahead of the second leg at the Allianz Arena.
The Spaniard's side were edging closer to the imperative second, as Robben's fine curling effort curled just wide of Fabianski post. Never liked in these parts due to his Chelsea connections, the Dutchman seemed unaffected by the persistent jeers from the Arsenal support and he produced a wonderful performance.
With their perfect display, it was easy to forget that this was a Bayern side shorn of Franck Ribery and Bastian Schweinstiger, with the latter fit enough only to take his place on the bench.
Guardiola was now becoming increasingly desperate for the second goal which would supposedly kill off the tie, and in his attempts to do so, brought on former Chelsea forward Claudio Pizarro in the place of Thiago Alacantara, who had impressed in the deep-lying role for the Bavarians.
But Bayern should have been awarded a spot-kick before after Koscienly had clipped Muller in the box. And instead of beseeching the Italian Rizzoli, he rose to his feet and played on.
After forty-five minutes of a demonstration of complete supremacy, Muller headed in Lahm's delightful chipped cross past the helpless Fabianski as Arsenal will certainly come to rue Ozil's languid penalty, with the German also liable of accusations of failure to take responsibility too.