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Arsenal boss Mikel Arteta said the Gunners aren't sure of the exact nature or extent of Lucas Torreira's injury after he had to be stretchered off in their 2-0 FA Cup win over Portsmouth on Monday.
The Uruguayan had to be withdrawn after quarter of an hour following a challenge from James Bolton.
Arteta said:
"He was in a lot of pain. He is in a brace at the moment, he will be assessed in the next few days, and we will know more then.