Arsene Wenger has revealed that medical intervention will be needed to solve Mesut Ozil's illness issue which will see him miss Arsenal's second leg of the Europa League last 32 clash against Ostersunds on Thursday (22 February).
The French coach, however, is confident that the German midfielder will be fit for the Gunners' Carabao Cup final against Manchester City on Sunday (25 February).
Ozil played the full 90 minutes against Ostersunds in the first leg last and trained with the first-team last week before falling ill on Monday (19 February). According to the Mirror, it is the fourth time in 14 months that the Germany international has been ill and Wenger confirmed that Ozil has a weak immune system.
The Arsenal boss was unsure as to the reason for the problem, but is hoping that the club's medical team can work towards improving his tolerance. He returned to training on Wednesday but the manager will not risk him for the Europa League game as he will be keen to keep him fresh for the game against Pep Guardiola's side on Sunday.
"His immune system is in trouble and I don't know why. We hope we can improve that medically," Wenger said, as quoted by the Mirror.
"He came back from Ostersund [where Arsenal won the first leg 3-0] on Thursday night, practised Friday and Saturday. Since Monday, he was in bed.
"Today was the first session. I would certainly have played him but because he was sick, he will have to work hard and he will not be involved against Ostersund. He should be OK for Sunday," the French coach added.
Ozil along with Aaron Ramsey will be key for the manager when they take on the Premier League title favourites at Wembley on Sunday and despite both training with the team on Wednesday following their return from illness and injury respectively, they will not be risked against the Swedish minnows.