Gabriel Martinelli has been sent for a scan to learn the severity of the ankle injury he sustained in the warm-up to Arsenal's FA Cup victory over Newcastle.
Martinelli, 19, was taking part in a passing drill when he appeared to twist his ankle awkwardly.
The Brazilian forward was unable to continue the warm-up and Reiss Nelson replaced him in the starting XI for Saturday's third-round tie.
Speaking after his side's 2-0 win, Arteta opened up on his tearful exchange with the youngster, who only returned from six months out with a knee injury in December.
And the Arsenal boss admitted he is facing a nervous wait to learn the magnitude of Martinelli's injury as he provided an update on his squad.
"We don't know how bad it is, he is getting a scan this morning," said Arteta on Monday. "We didn't look after the game because he was in a lot of pain.
"Yesterday he tested a little bit better so let's hope we have a scan today and it is not as serious and we can have Gabi back really soon, but we will know more tomorrow."
Arteta then provided a promising update on midfielder Thomas Partey, who has been absent with a thigh injury for over a month.
"Thomas now he’s been in full training for four or five days," said the Spaniard. "He’s completely asymptomatic.
"It was a little bit rushed to try and play him for Newcastle but I think he will be ready for Thursday."
The Gunners boss also discussed Gabriel Magalhaes, who tested positive for coronavirus in late December, adding: "Well Gabi he had a training session the other day. He tested positive.
"He had very mild symptoms so he’s missed a few weeks of training because he had to be isolated.
"It’s better now, we expect him to be training with us and couple of days and we will make an assessment whether we can have him or not on Thursday [against Crystal Palace ]."
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