Theo Walcott could sit out a second successive Arsenal match as the forward recovers from an apparent illness.
The London Evening Standard has reported that the England international sat out the 2-0 home victory over north London rivals Tottenham last weekend due to the problem, and was currently being assessed at the club's Colney training base.
Arsenal are set to travel to Germany to take on FC Koln in the Europa League on Thursday, and manager Arsene Wenger had hoped to deploy Walcott in the competition once more.
However, the 28-year-old may end up missing out on the trip if he is not passed fit enough to feature - the first time he would have sat out a Europa League game this term.
Wenger is likely to ring the changes once more as he looks to keep his first-team squad fresh after all-but-sealing passage to the last-32 of the UEFA club tournament.
Mohamed Elneny is likely to start in midfield against the struggling Bundesliga side, while defenders Rob Holding, Mathieu Debuchy and Calum Chambers will also be offered chances to impress.
I swear Arsenal fans are fucking weird. They'll abuse Theo Walcott who constantly gets goals in double figures and then praise Joel Campbell for huffing after being 5 mins on the pitch. Fucking terrible people— SaM (@Ignatiusly) 21 November 2017
One major decision Wenger will have to make is which understudy goalkeeper to deploy against Koln as he bids to give veteran shot stopper Petr Cech a much needed breather.
Number two choice David Ospina would normally deputise in Cech's absence, but third choice keeper Matt Macey impressed on only his second senior appearance against Red Star Belgrade earlier in November and may be called upon yet again.
If he is, it would be a huge blow to Ospina who has consistently called on Wenger to offer him more game time to boost his chances of going to the World Cup with Colombia next summer.
The 29-year-old has stated his desire to leave over the past two seasons following Cech's arrival, but Wenger has managed to keep him sweet with the offer of first-team football in knockout competitions.
Ospina has fully recovered from the groin problem which sidelined him for a fortnight, and his return will give Wenger a headache in one area of the pitch at least.