Arsene Wenger maintains it would be "criminal" for Arsenal to lose their focus against Dutch side FC Twente at Emirates Stadium on Wednesday night and miss out on the £20million windfall of the Champions League.
The Gunners eventually came through a stern examination by Steve McClaren's men in the first leg a fortnight ago in Arnhem, where late goals from captain William Gallas and Emmanuel Adebayor put them in the driving seat.
However, Wenger maintains there is still work to be done to ensure the north London club take their place among Europe's elite once again.
"That is a danger to be complacent, but there is so much at stake it would be criminal not to be focused," said Wenger, whose side reached the 2006 European Cup final against Barcelona in Paris.
"It is either being in the group stages on Friday or being out.
"Anything can happen at that level because we had a very difficult first leg - but it cannot be just because you were taking this game lightly."
Key midfielder Cesc Fabregas is expected to be back in the team after missing the start of the campaign with a hamstring problem.
Wenger, though, is not expecting an easy ride.
"The tie is not dead because you could see from the first leg how quickly we could score two goals from nothing," he said.
"We have done the job well at Twente, but the job is not over.
"We have to respect Twente and come into the game with a desire to win.
"It is not always easy to go into a match when you lead 2-0, but I want us to be positive and to win it."
The Gunners - who opened the previous campaign with a 21-match unbeaten run in all competitions - were well below par in Saturday's Barclays Premier League defeat at Fulham, and Wenger was clearly irked by the lacklustre display.
However, while the doom mongers may already be predicting a bleak outlook for the future of his young side over the next nine months, the Arsenal manager fully expects a response tonight.
"We were not good on Saturday and we lost the game, it is as simple as that," said Wenger.
"You cannot want the supporters not to take it to heart because we do. We are all very disappointed with our performance.
"We completely understand the critics because we were not good - but we promise we will come back and play well, to put a good performance in."
