Arsenal boss Arsene Wenger fears Mesut Ozil has a problem with his immune system.
The German has been ruled out of tonight’s Europa League clash with Ostersunds after missing two days of training through illness.
But he should be OK to play in Sunday’s Carabao Cup final with Manchester City despite a fourth bout of sickness in 14 months.
Wenger said: “Ozil’s immune system is a bit in trouble at the moment and I don’t know why.
“I hope we can improve that medically.
“I certainly would have played him against Ostersunds but because he was sick he won’t be involved.
“He came back from Sweden on Thursday and practised Friday and Saturday.
“On Sunday we were off and since Monday he was in bed.
“Today was his first training session and now he will have to work hard, but he should be OK for Sunday.”
Wenger had hoped to give his entire senior team the week off to prepare for Sunday’s final but will need some of them to also play tonight.
He confirmed that keeper David Ospina will start both games ahead of Petr Cech.
The Frenchman explained: “The situation has been clear since the start of the season. Ospina plays in the whole cup competitions.”