Mikel Arteta said Arsenal's stunning League Cup defeat by fourth-tier Fleetwood was "a very sad day" as the Premier League champions suffered one of the most embarrassing results in their history.

Arteta's side crashed out 5-3 on penalties in an incredible fourth round upset after the tie finished 1-1 in normal time.

Arsenal's Bruno Guimaraes had his penalty saved by Jay Lynch in the shoot-out and Conor Haughey scored Fleetwood's winner.

Aaron Loupalo-Bi's first-half goal had put Fleetwood ahead before Viktor Gyokeres equalised after the interval.

Arsenal's 16-year-old rising star Max Dowman was sent off for violent conduct in the closing stages.

Arteta paid the price for prioritising Sunday's Premier League trip to Liverpool as his decision to make nine changes backfired spectacularly.

The Gunners boss conceded Arsenal could have no complaints, admitting it was a painful moment in his reign.

"First of all, congratulations to Fleetwood for going through the next round. The manner that they have done it, and for us a very sad day," Arteta said.

"There is nothing to criticise the players for their attitude, their application.

"The determination, you could see that was there from the start, even with 10 men. But we conceded a really poor goal to start with that gave them some momentum.

"Obviously we have so much of the ball, so many chances, so many shots, and if you want the margins to be bigger than going to the penalties, you need to capitalise on that. And we didn't.

"It's football, that's the beauty of this competition. It's a very sad day."

Arsenal had moved level on points with Premier League leaders Manchester City after a 2-0 victory over Everton on Saturday.

But instead of extending their run of 11 wins from their 13 previous games, Arteta's team returned to north London red-faced after a loss that ranks among the darkest days in the club's glittering history.

"Zero problem attitude-wise. Otherwise, I would be here absolutely fuming. I'm sad, I think we are all sad. We have a massive responsibility to carry this badge in the best possible way," Arteta said.

"You don't capitalise, then you cannot go through to the next round. Unfortunately, we are out."