Speaking to the reporters after the West Ham game, Mikel Arteta said: "Emile Smith Rowe has got an injury in his knee and he's going to be out for weeks.
"We have an issue with him. He felt something in his knee and started to feel some pain after the game. We are assessing him but a bit worried with him.
"I'm honestly not going to give [a timeframe]. I did it once and got it totally wrong. We need to be cautious because we need to treat it in the right way."
Smith Rowe was not part of the squad against West Ham on Wednesday with Mikel Arteta heavily rotating his side for the Round of 16 EFL Cup defeat.
The midfield's knee issue has added to an injury crisis at Arsenal with the Gunners already having Thomas Partey and Gabriel Jesus on the sidelines.
