For almost an hour, the game was even at the Allianz Arena, then it all fell apart for the Gunners with goals by Robert Lewandowski in the 53rd minute, Thiago Alcantara three minutes and 10 minutes after that and then Thomas Mueller in the 88th minute to seal the defeat and perhaps Arsene Wenger's fate as manager, a job he has held for more than 20 years.
"We looked mentally very jaded and very vulnerable," admitted the Frenchman. "The last 25 minutes was a nightmare for us. We looked like we had no response."
In other years, Arsenal had a response and at least made things respectable, winning 3-0, 2-0 twice and 3-2 and tying 1-1 in the last five second legs. Even a 3-0 win in the second leg at the Emirates won't be enough to overcome the first-leg deficit. And who'll give the Gunners a chance?
Former Arsenal defender Martin Keown told BT Sport he felt for his former manager.
"It's almost embarrassing," he said. "They were outclassed, outplayed. Wenger has to be seriously considering his future now because it's embarrassing. I can't ever say I'd like to see him go, but this is his lowest point ever as Arsenal manager. He looked particularly wounded. I feel for him. He almost needs to be protected from himself. This is 20 years of work here, but this is a massive low point for him."
Wenger's contract is up at the end of the season. Another of his former players, Ian Wright, indicated Wenger told him his days at Arsenal were "coming to the end," though Wright quickly walked his comments back, saying it was only an impression he got. Wenger, for his part, said they had been together at a club dinner and it was late and he was tired and, well ...
Still, the sense is that Wenger won't seek to accept a new deal, and Arsenal is reviewing candidates to replace him.
The Daily Mirror reported that Borussia Dortmund's Thomas Tuchel, Juventus' Massimiliano Allegri, Bayer Leverkusen's Roger Schmidt and Monaco’s Leonardo Jardim were all on the Arsenal short list.
Does Wenger last the season? It would be hard to imagine owner Stan Kroenke and chief executive Ivan Gazidis pulling the plug on Wenger.
But Arsenal's next two EPL games before the return leg against Bayern are on the road against Southampton and Liverpool. The Gunners are tied for third place in the EPL but only a point ahead of Liverpool after dropping two of their last three games.
Arsenal has qualified in 19 consecutive UEFA Champions Leagues -- an English record, and the second longest streak in Europe behind Real Madrid's record of 20 -- and more than the streak, the UCL money means a lot to bottom-line conscious Arsenal.
Would Kroenke and Gazidis risk missing out on the Champions League next season for sentimentality if Arsenal's problems get worse? We'll know soon enough.