Arsenal defensive duo Hector Bellerin and Sead Kolasinac face late fitness tests to determine their availability for the clash with Eintracht Frankfurt.
The Gunners welcome the Bundesliga outfit to the Emirates on Thursday for the crucial penultimate Group F fixture.
A win or draw would see Unai Emery's side qualify for the knockout stages, while a Frankfurt victory would take it to the final game away at Standard Liege.
Both players have been struggling with hamstring injuries and will be assessed by the club's medical staff on the day of the game.
Bellerin was substituted towards the end of Arsenal's draw with Southampton at the weekend, while Kolasinac has been out of action since returning from international duty earlier this month.
Midfielder Dani Ceballos is already ruled out of the tie as he continues his rehabilitation from his own hamstring problem.
The Spaniard suffered the injury in the match with Vitoria on November 6 and is not due back in full training until mid-December.
Arsenal are in desperate need of a positive result against Frankfurt, who sit mid-table in the German league.
The return fixture saw the Gunners come away with three points in a 3-0 win, although their form has been inconsistent since.
Emery is now under increased pressure after odds on him being the next manager to leave his post in the Premier League were slashed to 1/2 by bookmakers.
He was due to host a managerial 'masterclass' at University Campus of Football Business (UCFB), Wembley, this week, but surrounding his position.
A message leaked on social media by the uni said: "It is with much regret that we can no longer present Unai Emery to UCFB students this Friday.
"We have noticed that there have been a number of negative comments aimed at Mr Emery when the guest appearance was initially announced."
Wolves boss Nuno Espirito Santo has emerged as a leading candidate for the role should Emery depart.
