But before that, Dowman was shown a straight red card with only four minutes left to play after kicking out in response to a strong Harrison Neal challenge.

A furious Arteta was shown by TV cameras giving the 16-year-old a stern telling-off as the academy talent made his way down the tunnel.

Asked what he told Dowman - who scored a brace at Ipswich Town in the previous round of the Carabao Cup - by BBC Radio 5 Live, the Arsenal manager said simply: "Something that we discussed already before the match." He refused to go into any more detail beyond that.

But Arteta did go on to say: "We knew when we prepared the context of the match, we were very clear on the things to expect, the things that emotionally we have to dominate."

"I haven't seen it [the red card] with the camera. You can't really see what happens. The decision was made by the referee and that's it. And even with 10 men, we have three big chances to score the second goal."

Speaking to Sky Sports, Arteta declared: "I prefer to watch it back properly and then I can assess the situation." Replying to a follow-up question on what the youngster can learn from the incident, the frustrated 44-year-old said: "Yeah, we all learn from everything, yeah."

But Arsenal legend Paul Merson accused Arteta of mistreating Dowman. He said on Sky's coverage: "It could easily have been a yellow, but you've got to remember he's 16, he's a kid and he wasn't having the greatest night and he's going to get frustrated.

"It's an old-fashioned tackle - he gets the ball then the player. If that's [Viktor] Gyokeres, who's an experienced international, he [Arteta] isn't doing that - but he does that to a 16-year-old kid. He's not the last person to get sent off for Arsenal, nor the first.

"If it was me, I'd have put my arm around him. It's still 1-1, they're still in the game. We all say things in life we wish we hadn't and if he [Arteta] could have that back, he'd do it differently."

Arteta said on going out of the cup: "First of all congratulations to Fleetwood for going through to the next round in the manner they've done it and the atmosphere they've created. A really sad day for us. I cannot fault at all the attitude of the players.

"I haven't seen anybody not doing what is required at this level. But we had so much of the ball, so many chances, so many shots. If you want the margins to be bigger than going to penalties, obviously you need to capitalise on that and we didn't. Football is about that.

"We gave them almost nothing in the whole game. We created so many chances and didn't capitalise on that. Then margins become so small, that's it. This is football, that's the beauty of this competition and especially in this country. It's a very sad day.

"The attitude was good, otherwise I would be here absolutely fuming. I am sad. I think we are all sad. We have a massive responsibility to carry this badge in the best possible way.

"It was nothing to do with effort or application or determination to win. With what we produced, it should have showed in the scoreline."

While Arsenal pressed for a winner, Dowman's red card and some late saves from Lynch helped force the shootout.

Fleetwood are now into the quarter-finals of the League Cup for the first time in their history while a reeling Arsenal team will look to bounce back at Anfield against rivals Liverpool on Sunday.