Defending FA Cup champions Arsenal crashed out of the competition at the first hurdle on Sunday, losing 4-2 to Nottingham Forest.
Eric Lichaj put his side into a surprise lead with a smart header from a free kick on the right wing, as Arsene Wenger's selection of a weakened team backfired.
Per Mertesacker equalised minutes later from a goalmouth scramble, but Lichaj grabbed another with a super volley, his first brace in England football.
In the second half, Forest extended their lead with a Ben Brereton penalty after a poor challenge from Rob Holding on Matty Cash.
A dreadful Jordan Smith error allowed Danny Welbeck to slot into an empty net to pull one back for the Gunners, but Kieran Dowell scored a fortunate second penalty to wrap things up, when he may have double-touched the ball from the spot.
A frantic end to the match saw Joe Worrall sent off for a second yellow.
Ben Brereton shows incredible promise for an 18 year old: Few players his age in the Premier League show such calmness, especially in big games. Brereton was direct and fearless, and showed no little technique in his approach play before converting the second-half penalty.
MAN OF THE MATCH
Eric Lichaj (Nottingham Forest): His first goals set the tone for Forest. The first was about being alive to the ball before the slack opponents of Arsenal. The second was a display of confidence and of ability. If his teammates repeat this performance they will climb up the league.