Well... it's certainly been an interesting start to the Champions League knockouts!

Can Arsenal, and Arsene Wenger, recover from this mauling?

Keep an eye on the BBC Sport website for more reaction. My work here is done. Goodnight!

Pat Nevin
Ex-Chelsea winger on BBC Radio 5 live

Three of their goals came within 10 minutes, two minutes after their one defender comes off. It can’t be allowed to happen that one player is the core and everything falls apart without him.

A lot of clubs will look at Laurent Koscielny and think ‘we can drag him away’. He would improve Bayern’s back line.

Birch1966: I enjoyed Wenger in the early years, winning with George Graham players. For me Graham rebuilt Arsenal. Won Titles.

Empire Antiques: Wenger deserves more respect for what he has done for your club , although it probably is time to go.  

Bayern Munich boss Carlo Ancelotti: "The result is really important, we have the advantage. We have to prepare for the game in London well - we want to play the same as we did tonight. We want to avoid problems. This is only one game."

Image source, AP

Arsenal boss Arsene Wenger: "It was a strange game. In the first half we played quite well. We had two chances just before half-time. After that we got a few blows. 

"After the third goal, we lost our organisations and we looked very jaded mentally and vulnerable. The last 25 minutes was a nightmare for us. We looked like we had no response."

Aaron Theaker: Wenger please leave my club alone. You've made us go from one of the most feared clubs to the biggest Joke in world football

The Mizo: Officially the laughing stock of the football world. Wenger must now leave. Going backwards

Saroj Gurung: 5-1 San Siro was Arsene's best night. This was his worse and probably the end of the road. 

Pat Nevin
Ex-Chelsea winger on BBC Radio 5 live

My concern for Arsene Wenger and Arsenal is when they get to the higher echelons of the Premier League and Champions League, they get found out. They’ve fallen behind.

Players won’t come to Arsenal if Chelsea, Manchester United, City or maybe even Liverpool want them. It’s been too long. The problem is keeping the couple they've got. The last caller wants Arsenal to sign Robert Lewandowski. In your dreams. The stagnation has been there too long.

It feels very close to the end, and I’ve never said that about Arsene Wenger before.

Bayern Munich boss Carlo Ancelotti: "We played fantastic football. The result is important, but we still have a game in London. We have to show the same passion.

On the superb Thiago: "He played very well and got two goals to boot. It was a perfect performance."

Image source, AP

Chris Leonard: The gun on the Arsenal badge need's replacing with a pea-shooter.....What we were and what we are now   

Richy: Arsenal have so many average, weak players who keep getting new contracts. Wenger was great but not anymore.  

Ken Kay: Arsene Wenger shouldn't be judged on tonight. Whatever has just happened shouldn't tarnish 20 years work.

Arsene Wenger didn't stick around in his post-match news conference. Plenty of talk about his side being mentally weak. 

Henry Winter
Chief Football Writer for the Times on BBC Radio 5 Live

It’s just from top to bottom with Arsenal, there’s no leadership. They have a silent owner who is sleepwalking towards the abyss. Their manager’s best days are behind him. Everyone can see that. He’s been overtaken by Conte, Klopp and other managers.

It’s a lack of leadership on the pitch, long-running problems. This isn’t a great surprise, although it was particularly shameful. It could have been a tennis score without David Ospina.

Former England defender Rio Ferdinand on BT Sport: "What is the remit from the Arsenal board. Is it to qualify for the Champions League? Or is it to win the Champions League or Premier League? I'll be disappointed if Arsene Wenger is remembered for this period of his career."

Former Arsenal defender Martin Keown on BT Sport: "He looked particularly wounded. I feel for him - he almost  needs to be protected from himself. This is 20 years of work here. He's been magnificent for the club. This is a massive low point for him. This brings forward the change that looks likely at the end of the season.

"I think it will be him that makes the decision. The realisation that the decision needs to be made is more apparent tonight."

More from Arsene Wenger: "I do not look for excuses. It is a shock of course to lose at that level. We made everything wrong, the fifth goal shows that.

"These kind of games you need to be focused for 90 minutes. I felt the third goal was a killer for our players after that we had no response."

Asked if it is his lowest point: ""How I feel I don't think is the most important but of course it is disappointing."

Do Arsenal need a miracle: "We have to recover first and focus on the next game."

Arsenal boss Arsene Wenger, speaking to BT Sport: "It is difficult to explain. I felt we had two good chances to score just before half time. I felt we were unlucky for the second goal the referee gave a corner for us at first. Then we concede the second goal and then the most important was that we lost Koscielny. We collapsed. 

"Overall I must say they are a better team than us, they played very well in the second half and we dropped our level. We were a bit unlucky we dropped our level and they were better than us."

Image source, Rex Features

Arsene Wenger is speaking to BT Sport now and he sounds low. As low as I've heard him sound for a long time. 

Full quotes coming up next.

Henry Winter
Chief Football Writer for the Times on BBC Radio 5 Live

Arsenal are a laughing stock. There is money there, it’s a myth that there isn’t. Wenger has lost his leadership skills, there’s no invincible streak in him anymore. The Arsenal fans I was talking to today all knew this was going to happen.  

Image source, Rex Features

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Pat Nevin
Ex-Chelsea winger on BBC Radio 5 live

Laurent Koscielny is massive. He’s a world-class player and he's stayed at Arsenal so long. But as soon as he came off, they were shambolic. But Bayern spotted that.

Will Sanchez stay? To be fair I would be completely astounded, with his body language and the way they are doing at the moment.

Stick with his here for reaction from Arsene Wenger. He is due to speak to the media very soon. Whatever he says is sure to be interesting...