That's about all the reaction that we are getting tonight I think.

Join us back here on Wednesday for Spurs and Leicester?

Deal.

Ally McCoist
Former Scotland striker on BBC Radio 5 live

When Barcelona travel to Celtic Park the atmosphere will be absolutely unbelievable.

You wouldn't expect it to get to the Barca players, they'll probably enjoy it.

But the result that Celtic have got tonight gives them a little bit of hope.

Anthony: Pep Guardiola got his tactics SPOT ON tonight, Messi and co couldn't handle City second half..

Andy Greary: One game does not make a season. Pundits & fans over reacting to MC win. Pep equals overrated.  

Dr Holmes: The Pep has well and truly ARRIVED!!

Patrick Traile: Very good win indeed city! Still no Pep effect, Pellegrini would have done it eventually.

Is there a 'Pep effect'? Have your say at #bbcfootball on Twitter.

Arsenal

Arsenal manager Arsene Wenger: "You wanted Mesut Ozil to take his chance earlier, but in the end he shows he has enough skill to prove he was right.

"I believe the hardest thing is to be consistent at the top level, but hopefully we can now go further [in the competition].

"We need to maintain the quality of our results until the match against Paris St-Germain and then hopefully we will be in a position to finish top of the group."

Manchester City scored more goals tonight against Barcelona (3) than they had in their previous five Champions League games against them (L5).

An English side has scored 3+ goals in a Champions League group stage game against Barcelona for the 1st time since 1998-99 (v Man United).

Image source, Getty Images

Aaron Vallance: City super 3-1 performance not so different to 4-0 loss. Shows how games change on a sixpence and how results determine narrative.

Meer Shah: Looks like Guardiola has finally made a Sterling impact at Man City.

Barcelona manager Luis Enrique: "It was one of the best 40 minutes we have played on a stage like this against top-quality rivals.

"After the error for 1-1 we had a bad time. When you concede in that way it is normal that you go through a bad period. We hoped to continue to dominate but couldn’t because of errors we made and pressure from the opponent also. 

"We did not have as much possession and we made errors, we were not able to control the game in the same way. First 40 for us and 50 for them and the score reflects that."

Asked if he is worried or surprised by his side's defensive errors: "They are normal things that happen in games, perhaps when you play so well for 40 then when after that things don’t go to plan it is a strange feeling but they played very well and pressed aggressively to provoke more errors than they made."

Image source, EPA

Manchester City

Manchester City manager Pep Guardiola: "They had an amazing 30 minutes, we had a lot of problems but our first goal helped us a lot."In the second half we created a lot of counter attacks. I am so happy for the guys, it is the first time we have beaten the best team in the world."

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

Image source, Getty Images

It looked like City are beginning to come of age in Europe. It takes time, but it looks like Guardiola has come in and accelerated City because of his intelligence.

Guardiola has this impact. You look at Sterling and what he's done to him - it's clearly got the manager's impact written all over it. 

Olivier Giroud has scored five of Arsenal’s last eight goals away from home in the Champions League.

Mesut Ozil’s four goals in his last two Champions League games are more than he registered in his first 22 appearances in the competition for Arsenal (3).

Our chief football writer Phil McNulty is answering your questions from Etihad Stadium after watching Manchester City's 3-1 win over Barcelona. And he's also taking questions on any other issue from tonight's action that takes your fancy - so get involved on Facebook Live.

Ally McCoist
Former Scotland striker on BBC Radio 5 live

Raheem Sterling looks like a completely different player, not just in his attitude but his general game awareness. 

His pass for the first goal was absolutely out of this world, he had the composure to set-up Ilkay Gundogan.

Then in the second-half he sprung at the right times and made interceptions. He just looks like someone who is really enjoying his football and who has a new lease of life.

Celtic manager Brendan Rodgers: "I thought we should have won the game.

"I thought we were the best team, but I am really proud of the players tonight.

"I said we needed to play with personality and the personality we showed was outstanding.

"We were brave on the ball, had speed on the counterattack and we had chances.

"An outstanding team performance."

Image source, Reuters

Arsenal

Arsenal manager Arsene Wenger: "We needed to keep our composure. I believe we were surprised by the speed of their start but after that we came back to 2-2 which was positive. We were less fluent in the second-half but we eventually got a goal close to the end.

"Ludogorets maintained their intensity for 90 minutes so it was more difficult than at the Emirates where they dropped off."

Image source, Getty Images

Ally McCoist
Former Scotland striker on BBC Radio 5 live

The one thing that would be a tragedy would be if City don't take the confidence from this.

Manchester City were fantastic in the second half. It would not have been a shock to me had City scored again. They were in many ways playing Barcelona at their own game, which is a very dangerous thing to do.

The confidence that the players and the manager should take from this performance is invaluable. 

Image source, Getty Images

Arsenal

Arsenal midfielder Aaron Ramsey: "Ludogorets have some top quality in their team and caught us on two counter-attacks.

"On a personal level I'm delighted to be back getting minutes under my belt. My target is just to stay fit and keep playing. We are in good shape going into the next game."

Olivier Giroud: "I am pleased for the team, it was a great delivery from Aaron for my goal. I was in the stands at the Emirates in the reverse fixture and they impressed me a lot, so we knew it wouldn't be easy tonight. But we never gave up and we keep trusting in our game, it's a good evening for us.

"We are in a strong run, we want to carry on our momentum even though it is early in the season."

Image source, Reuters

The Champions League group stages are often criticised, too many dead games, not enough entertainment - but tonight served up the goods for sure. 

Let us know your thoughts on tonight's Champions League football at #bbcfootball on Twitter. 

Meer Shah: Call it what you want. Epic. Disastrous. Determined. Fact is, Arsenal got the job done. That is all that matters.

Lucas JJ: What a performance from City tonight. Every single player has run their socks off.

Kieran Hooper Burns: Great effort from Celtic. Proud of that, unlucky not to win in the end.

Ally McCoist
Former Scotland striker on BBC Radio 5 live

There was some shocking defending to start with from City, but what I would say about their equaliser is how well they pressed and forced the error from Roberto.

Manchester City

Manchester City midfielder Kevin de Bruyne: "It was a big game for us, we were under pressure. We made a few mistakes but in the second half we were very good and deserved it. Everybody knows the style we play. Everything fell in the right place."

Ilkay Gundogan: "We started a bit nervously but after we scored we had our confidence back and the second half was incredible. We dominated Barcelona."

Image source, Getty Images