The Premier League champions crashed out 5-3 on penalties in an incredible upset after the fourth-round tie finished 1-1 in normal time at Fleetwood's home ground of Highbury.

Arsenal's Bruno Guimaraes had his penalty saved by Jay Lynch in the shootout before teenage defender 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 manager Mikel Arteta made nine changes to his starting side, but after a ragged first-half display he sent Norway midfielder Odegaard on for the second period.

The visitors, last season's losing finalists, managed an improved performance but still missed several chances before teenage rising star Max Dowman was sent off five minutes from the end of normal time.

"It's very frustrating to go out," Odegaard said. "Obviously, the way we've played was not on the level. We need to do much, much better than we did.

"Frustrating, but congratulations to Fleetwood, and we look forward to the next game already and bounce back.

"They did well so we have to give them credit, but I think (it) was about us not being on our level; we need to do better. I thought we improved during the game, but again, we need to step up even more - so that's a shame."

Arsenal now just have days to get the defeat out of their system ahead of what promises to be a tough match at Liverpool on Sunday, with the Gunners having drawn level on points with Premier League leaders Manchester City last weekend.