Manager Arsene Wenger said Arsenal have only a "small chance" of reaching the Champions League knockout stages after a 5-1 thrashing by Bayern Munich.
Defeat leaves the Gunners bottom of Group F, six points behind leaders Bayern and second-placed Olympiakos.
Arsenal must now beat Dinamo Zagreb and Olympiakos in their final two games, and hope the Greek side lose at Bayern.
"There is still a chance to qualify," said Wenger. "We have to realise that our chance is at a minimum."
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The Gunners' hopes of reaching the knockout stages for a 13th successive season are in danger after they were outclassed by Pep Guardiola's Bayern, suffering their record-equalling European defeat.
After Robert Lewandowski, Thomas Muller and David Alaba scored in the first half, Arjen Robben added a fourth with his first touch 10 minutes into the second half.
Olivier Giroud pulled one back with a well-taken volley before Muller added his second a minute from the end.
"It leaves us short," said Wenger. "It will be very tight but we have to fight until the end. Let's hope Bayern beat Olympiakos and we win at home against Zagreb. That leaves us with a chance to qualify from the last game.
"It's a small chance but there is still a real one."
'We watched them play'
Arsenal's performance was in stark contrast to the 2-0 win over Bayern at Emirates Stadium a fortnight ago, and Wenger bemoaned his side's defending.
Centre-back Gabriel, playing instead of Laurent Koscielny after the French defender injured a hip, struggled to cope with Bayern's attackers, who were ably supported by a fast-paced midfield.
"Defensively we were extremely poor. We never looked like a team that could play like a unit," said Wenger, whose team host Tottenham in the north London derby on Sunday (16:00 GMT).
"The crazy thing is we looked like we could create chances but overall we had a disappointing performance.
"There was no pressing, no concentration, no challenges. We watched them play. They are a good side and we paid for it."
Duo doubtful for Spurs game
The Gunners head into Sunday's game level on points with Premier League leaders Manchester City.
Right-back Hector Bellerin injured his groin in the build-up to the match in Munich and Wenger said both he and Koscielny are doubts for the game at Emirates Stadium.
"I don't think Bellerin will be available, or Koscielny, we will have to see on Friday or Saturday," said Wenger, who is without 10 first-team players.