The Frenchman lost a third-round tie for the first time, as his much-changed side went down in an action-packed clash at the City Ground.
Wenger has become the competition’s most successful manager, winning it seven times since taking charge of Arsenal in 1996, but the country’s longest-serving boss was undone by Forest caretaker manager Gary Brazil yesterday.
Eric Lichaj scored twice either side of Per Mertesacker’s equaliser, before penalties from Ben Brereton and Kieran Dowell sandwiched Danny Welbeck’s goal in a 4-2 win for the Championship side.
Forest finished the match with 10 men, as Joe Worrall was shown a straight red card in the final minute for a late challenge on Chuba Akpom, but that did not dampen the home celebrations at the final whistle.
Dejected, but magnanimous in defeat, Wenger said: “It hurts very much because we have won the FA Cup three times in the past four years.
“On the other hand, it is a very difficult competition to win, but it hurts to go out in the third round... for the first time, but we knew it would be very tricky, it is a difficult place to come.
“I congratulate Nottingham Forest on an outstanding performance. They won decisive challenges and were always dangerous going forward and, overall, I think they deserved to win.”
Wenger’s influence on matters was reduced as he watched from the stands. The 68-year-old served the first of a three-match touchline ban after being hit with a misconduct charge and a £40,000 fine by the Football Association for his recent public criticism of referees. Asked if his team missed his input from the technical area, he said: “No, I wouldn’t say that. We were just not good enough, not anywhere. Not in the front, not in the middle, not at the back, and we paid for it.
“They looked sharper and had more chances, it was an outstanding performance from Nottingham Forest.”
Wenger made nine changes from the team that started the midweek Premier League draw with Chelsea, with just Rob Holding and Ainsley Maitland-Niles keeping their places in the team.
Arsenal clearly lacked their usual fluency, but the Gunners boss refused to use it as an excuse for the defeat.
“We have had a difficult schedule. Many players were on the edge and we play again on Wednesday,” he said. “It was nearly impossible and I can understand that the selection was questioned, but as well it would be an easy excuse, as we had eight or nine international experienced players on the pitch. That would be the wrong excuse, for me. We repeated the same mistakes over and over — once, twice, three times — and that is where we are guilty today. They were better than us, which is disappointing.”
Yesterday’s match was Brazil’s second in charge since being asked to step up from his academy role, following Mark Warburton’s sacking.
Asked if he thought he would still be in charge for Forest’s fourth-round tie towards the end of the month, he said: “No. I don’t know how long it will be, but the communication inside the club is really good and we have been asked to take the first team on a game-by-game basis and we are really comfortable doing that.”
On the game itself, the 55-year-old said: “I’m very proud of the players and I think the senior players led by example. The young players handled the occasion well, too, and I am very pleased with the group as a whole.
“I never felt at any stage that we weren’t going to win the game. I felt very comfortable in the match. There were some good players in Nottingham Forest shirts today and to a man I thought we worked really hard.
“Whoever the next manager may be, he has a very good group of players.”
Smith, Lichaj, Worrall, Mancienne, Traore, Vaughan, Osborn, Cash (McKay 87), Dowell (Mills 90), Clough (Walker 56), Brereton.
Henderson, Bouchalakis, Cummings, Vellios.
Ospina, Debuchy (Akpom 87), Mertesacker, Holding, Maitland-Niles, Elneny, Willock (Nketiah 65), Walcott, Iwobi, Nelson, Welbeck.
Chambers, Reine-Adelaide, Da Silva, Macey, Osei-Tutu.