Mesut Ozil and Aaron Ramsey have not travelled with the rest of the Arsenal squad to Belarus for Thursday's Europa League last-32 first-leg tie against BATE Borisov.
The German missed Saturday's 2-1 victory at Huddersfield Town after he reported sick.
Ramsey missed training on Wednesday morning because of a knee problem and also sits out the Borisov clash.
It was confirmed earlier this week that the Wales international will join Juventus when his contract with the Gunners expires in the summer.
Arsenal boss Unai Emery is expected to name a strong team against BATE Borisov, who they beat 4-2 and 6-0 in the group stage of last season's Europa League.
Pierre-Emerick Aubameyang was able to train on Wednesday and is fit to play after he missed the Huddersfield win while midfielder Granit Xhaka is available following a groin injury.
Emery has still to decide whether Petr Cech or Bernd Leno will start in goal in Belarus. Arsenal, 6/1 to win the Europa League this season and 3/1 to finish in the top four of the Premier League, can be backed at 1/1 to keep a clean sheet on Thursday.
The Gunners have failed to keep a clean sheet in 13 away Premier League matches this season.