Mikel Arteta described Arsenal's FA Cup third-round defeat to Manchester United on Sunday as a one-in-a-thousand occurrence after losing in a dramatic penalty shootout at Emirates Stadium.

Bruno Fernandes put the visitors in front on 52 minutes before Diogo Dalot was sent off nine minutes later for a late tackle on Mikel Merino.

Gabriel Magalhães equalized in the 63rd minute, but despite playing almost an hour against 10 men, Arsenal were unable to find another breakthrough, with captain Martin Ødegaard missing a penalty 18 minutes from the end of normal time.

United felt justice was done given the spot kick was awarded despite Harry Maguire making minimal contact with Kai Havertz in the box (there is no VAR in the FA Cup until the fifth round). But United were left to defend for long periods afterward, as Arsenal probed for a winner.

The hosts registered 26 shots in total, with Havertz guilty of two bad misses. He was also the only player to fail in the shootout, as Altay Bayindir saved his spot kick to give Joshua Zirkzee the chance to win the game and set up a fourth-round tie for United at home vs. Leicester City.

"It's unbelievable," Arteta told the BBC. "Obviously, you measure the performance and what we did in relation to the position, you know, you deserve to win the game by a mile. But the reality is we are out, and the only thing that's going to be judged is that, but internally, I can't.

"I love my players. I love our team and I love how good they are and what they do because in a thousand games, you should lose one, and probably it was this one. You have to understand this as well, it's part of our industry, our game and move on because you don't have time to do that, because on Wednesday we have a massive one."

Arsenal face a home clash with north London rivals Tottenham in the Premier League on Wednesday.