Mikel Arteta has confirmed that Thomas Partey "will miss the next few matches" but does not think he rushed the Ghanaian back.
Arsenal take on Dundalk on Thursday in their final Europa League group game.
But they will face their Irish opponents without their summer signing who hobbled off injured in Sunday's north London derby.
Partey had been absent for several games before he returned at the weekend.
Arteta confirmed that he has aggravated the same issue but maintained he was not bought back earlier than planned.
He said: "I don't think it was a bit too early because he was completely fine to play."
"He got injured in the same area. Not exactly the same spot, but similar as it was before. We MRI [scanned] him yesterday.
"There was an injury there and he will miss the next few matches.”
Partey's absence has coincided with a poor run of form for the Gunners.
Arsenal have lost three of their last four league games as they languish in the bottom half of the table.
Pressure is growing on Arteta but the Spaniard has laid down the gauntlet to his established stars, many of whom aren't performing.
Pierre-Emerick Aubameyang signed a lucrative new deal in the summer but has returned just two goals this term.
And the Arsenal boss has warned his frontman that he is not above being dropped.
"No one is undroppable at the end of the day," he said.
"You have to find the right players to win football matches but we cannot forget what Auba has done for this club and what he's done in recent months, not years ago.
"And as well because I see how he is training, how he is behaving and how much he wants to turn the situation around."
