Arsene Wenger acknowledged that "the level was too high" for his young Arsenal players as they lost 3-0 at Sheffield Wednesday in the Capital One Cup.
However, he said his main regret was including "too many experienced players" in the squad on a night when Alex Oxlade-Chamberlain and Theo Walcott suffered injuries.
Arsenal went into the match looking stay on course for a first League Cup success since their victory over Wednesday in the 1993 final, but they were well beaten by the Championship side.
Ross Wallace and Lucas Joao put the Owls ahead before the break and Sam Hutchinson rounded off the scoring in the 51st minute.
Wenger, who had backed fringe players Joel Campbell and Calum Chambers to impress ahead of the match, said he now recognises that the side he selected had "no chance" to secure a result.
Arsenal also fielded Alex Iwobi, Glen Kamara, Ismael Bennacer and Krystian Bielik over the course of the night and Wenger said: "The level was too high for the young players. They are not ready to play at this level. "
Wednesday are currently on a seven-game unbeaten run in the Championship that has seen them climb to ninth in the table, and Wenger added: "Because of many foreign players playing in the Premier League, you have more and more good players playing going down to the Championship and to play with young players against Championship players becomes difficult.
"The level of the Championship has gone up and you see that once you have not enough of experience to deal with these types of games, you have no chance to win it."
He said he would have "loved" to have won the match but that losing two senior players to injury was a bigger source of regret than losing the match, and that was why Nacho Monreal and Gabriel Paulista had not been introduced from the bench.
"I have to manage the workload of the players and at the end of the day I still think I brought too many experienced players here," he said. "We lost two players. Once I lost two players, I had Gabriel and Monreal and I did not bring them on as we could not afford to lose any more players."
Wenger suggested exiting the competition would help his side in other competitions but feared the impact of the injuries to Walcott and Oxlade-Chamberlain ahead of the games against Swansea and Bayern Munich.
"I'm concerned because our next game is a big game on Saturday," he said. "We have the Champions League against Bayern Munich coming up. Already we are now short. To lose two players tonight, two offensive players, is damaging for us."