Fleetwood shootout hero Conor Haughey admitted he had not even practised penalties before hitting an emphatic spot-kick that dispatched Arsenal and secured a Carabao Cup upset his manager Matt Lawlor described as “mental”.

After Bruno Guimaraes was denied by Jay Lynch, the 19-year-old Haughey rifled his shot into the top left corner, securing a 5-3 shootout win after a 1-1 draw and sparking a pitch invasion at Highbury.

Despite his tender years, the Northern Ireland Under-21 defender never looked to have the slightest doubt as he strode forward.

“It’s the way I’ve been brought up,” he said. “Obviously I’m a Belfast boy. Where I grew up, if you’re not confident you get eaten up, so you just take it in your stride whatever you do.”

His belief came despite not getting as far as practising spot-kicks ahead of a match in which few will have believed Fleetwood had any chance – a side 18th in League Two coming up against the Premier League champions and beaten finalists in last season’s competition.

“We all trust in each other’s ability, we train with each other every day,” Haughey said. “You already know where you’re putting it and just need to be technically good enough to put it where you want to.”

Fleetwood took a shock 21st-minute lead through Fulham loanee Aaron Loupalo-Bi, but Arsenal’s half-time introduction of Martin Odegaard changed the dynamic and Viktor Gyokeres quickly levelled as they piled on the pressure.

Fleetwood stood strong and, after the 85th-minute dismissal of Arsenal’s prodigy Max Dowman for a petulant kick, held on for their moment of glory.

“I’m going to be honest now, I hoped, dreamed and we prepared for a game like that,” Lawlor said. “But if you would have told me that would happen, I wouldn’t have probably believed you.

“That we’d be through to the Carabao quarter-final and beating the champions of our country, I think it’s mental…

“When it went to penalties, obviously I hoped for a winner. I said to the lads it wouldn’t change my thoughts and my feelings on the proudness that I felt in the performance and the way that we dug in and had to dig in.

“Let’s have it right, the difference in not just quality, I mean infrastructure, quality, budget. I don’t think there’s a comparison as to how big of a jump that is, what we’ve just achieved tonight.”

A disappointed Mikel Arteta said: “Congratulations to Fleetwood. I have nothing to fault the players (for) in terms of their attitude, application, the intensity they put in throughout the game.

“But when you are that superior, you give nothing to the opponent apart from the first action that we defended so poorly, and you generate so many situations, actions, volume of shots and chances, you have to score three, four, five, and capitalise on that.

“If you don’t there are no margins, that’s a reality and then you have to get through the round on penalties. We didn’t do that, so the probability is always there.”

Arteta said he had not spoken to Dowman about his dismissal but added: “When we prepared the context of the match, we were very clear on the things to respect, the things that emotionally we have to dominate, it was very clear.”