Arsene Wenger has admitted that his young Arsenal squad were "not ready" for their League Cup match against Sheffield Wednesday at Hillsborough.
The Gunners were beaten 3-0 by the Championship side after losing Theo Walcott and Alex Oxlade-Chamberlain to injury inside the opening 20 minutes.
"It was a very bad night for us. We lost two important players in the first part of the game and then we were not at the level we needed to be," BBC Sport quotes the manager as saying.
"Congratulations to them, they were faster, sharper and more decisive than us. We could not create anything. We were very naive when defending.
"We cannot master how people will react. I left six players at home and I still lost two to injury. The level was too high for the young players tonight. They are not ready to play at this level. We are short now with the injuries. It is a big blow for us."
Youngsters Alex Iwobi and Glen Kamara both started the match for the visitors, while Ismael Bennacer and Krystian Bielik both featured off the bench.