FA Cup holders Arsenal were stunned 4-2 by second-tier Nottingham Forest in the third round on Sunday.
Eric Lichaj scored twice for the hosts either side of a Per Mertesacker equaliser to give Forest a 2-1 halftime lead.
Ben Brereton, one of seven players aged 23 or under in the Forest side, made it 3-1 from the penalty spot in the 64th minute.
Danny Welbeck took advantage of an error to pull a goal back for Arsenal with 12 minutes left but Forest were awarded another penalty which Kieran Dowell converted.
It is the first time Arsenal have lost in the third round since 1996 and the first time since Arsene Wenger took over.