Manager Arsene Wenger has admitted using "too many experienced players" after Alex Oxlade-Chamberlain and Theo Walcott were injured in Arsenal's 3-0 League Cup loss at Sheffield Wednesday.
Walcott replaced Oxlade-Chamberlain but left the field on 18 minutes and both will have scans on muscular injuries.
The Gunners boss said the injuries to both forwards were a "big blow".
"We are short now with the injuries," added the 66-year-old Frenchman, who has six other first-team players out.
"I have to manage the workload of the players and at the end of the day I still think I maybe brought too many experienced players here."
The FA Cup holders barely threatened as goals from Ross Wallace, Lucas Joao and Sam Hutchinson sent the Championship side into the quarter-finals.
Wenger said he would have "loved" to have won the tie but, referring to his growing injury list, he added: "With the squad we have got now, we cannot keep in all the competitions."
|Arsenal's injury concerns|
|Aaron Ramsey (hamstring - end of November return)||Tomas Rosicky (knee - unknown return)|
|Jack Wilshere (leg - unknown return)||David Ospina (shoulder - November return)|
|Danny Welbeck (knee - Christmas)||Theo Walcott|
|Mikel Arteta (ankle - unknown)||Alex Oxlade-Chamberlain|
Wenger made nine changes for the 3-0 defeat but still included Olivier Giroud, Per Mertesacker, Mathieu Flamini, Petr Cech, Mathieu Debuchy, Kieran Gibbs and Calum Chambers.
But Wenger said the level was "too high" for the younger players he selected.
Midfielder Glen Kamara and forward Alex Iwobi - both 19 - made full debuts in the last-16 tie, while 17-year-olds Ismael Bennacer and Kristian Bielik came off the bench.
"They are not ready to play at this level," said Wenger. "We lost two players and after that I had Gabriel and Nacho Monreal on the bench but I couldn't bring them on because I couldn't afford to lose any more players."
Arsenal will wait 48 hours for the result of scans on England internationals Walcott and Oxlade-Chamberlain.
Wenger also called the latest injuries "damaging" as his side - second in the Premier League - travel to Swansea City on Saturday before a key Champions League game at Bayern Munich four days later.
Defeat at Hillsborough ended a four-game winning run for the Gunners, who have not won the League Cup since 1993, when they beat Wednesday 2-1 in the final.
"They were faster, sharper and more decisive than us," added Wenger. "We could not create anything. We were very naive when defending."