Neither Ben White nor Fabio Vieira were involved in team training with Arsenal ahead of the Gunners' Champions League showdown with Lens in Group B on Wednesday evening.
The Gunners reunite with Les Sang et Or requiring only a point to advance to the Champions League knockout stages, although their top-two finish could even be confirmed before kickoff if Sevilla beat PSV Eindhoven in the 5.45pm contest.
Victory for Mikel Arteta's men would also send them through to the last 16 as group winners with a game to spare, as they hold a four-point lead over Lens and PSV thanks to a record of three wins and one defeat from their four Group B matches so far.
Several Arsenal players have been in the care of the medical team over the past few weeks, with Emile Smith Rowe and Jurrien Timber both absent due to knee injuries, while Thomas Partey is still nursing a thigh concern.
None of the trio will be fit to face Franck Haise's side in midweek, and Arteta has seemingly been handed two fresh concerns to work around, as White and Vieira did not train with the team on Tuesday.
White had sustained a knock in Arsenal's most recent Champions League win over Sevilla before the international break, which ruled him out of the Gunners' 3-1 success over Burnley on November 11.
The England international - who was only a substitute in Arsenal's 2-1 loss to Lens last month - recovered in time to make the bench for Saturday's Premier League clash with Brentford and was brought on in added time to help see out a 1-0 win.
After the bulk of Arteta's team emerged onto the London Colney training fields, White walked out with a strength and conditioning coach to carry out individual work, pouring doubt over his availability for Wednesday.
Meanwhile, Vieira was due to return to the squad for the European affair, as the Portuguese playmaker served the first of a three-game domestic ban at the weekend following his red card against Burnley.
However, Vieira was absent entirely from the main group on Tuesday, and Arsenal have not revealed the reason for the midfielder's absence, but Arteta will be expected to deliver an update in his pre-game press conference later in the day.
While Vieira would have been unlikely to force his way into the first XI, White's possible issue could see Takehiro Tomiyasu retain his place in the backline, where David Raya is expected to return in goal.
The Brentford loanee could not face his parent club on Saturday evening and handed the gloves over to Aaron Ramsdale - making his first start in the Premier League since September 3 - where the Englishman kept a clean sheet despite two first-half howlers.
Arteta also welcomed 16-year-old Ethan Nwaneri - the Premier League's youngest-ever player - and 17-year-old Myles Lewis-Skelly to first-team training on Tuesday after both teenagers returned from representing England at the Under-17 World Cup.
The Gunners succumbed to strikes from Adrien Thomasson and Elye Wahi after Gabriel Jesus had opened the scoring against Lens last month, and Wednesday's game will mark their sixth meeting with the French team in all tournaments.
Arsenal have failed to win any of their previous three Champions League clashes against Les Sang et Or, although they came up trumps in both legs of their 1999-2000 UEFA Cup semi-final tie before losing to Galatasaray in the final.
