Arsenal midfielder Martin Odegaard is a major doubt for the club's next two games.
The Norwegian missed Thursday's 1-1 draw with Slavia Prague in the Europa League quarter-finals.
And Mikel Arteta confirmed Odegaard was doubtful for the second leg next week in Prague, along with Sunday's trip to Sheffield United.
Asked if he was concerned Odegaard might be missing for the long term, Arteta said: "We don't know.
"He wasn't able to play today and he will be out, I think, for the next game or two. But we don't know yet."
