Standard Liege striker Milan Jovanovic admits he is "scared" by an atmosphere of over-confidence ahead of the second leg of their Europa League last-16 tie against Panathinaikos.
The Belgians took a huge step towards a place in the last eight after winning 3-1 in Greece last week.
However, Jovanovic insists they cannot afford to think the job is done.
"For several days I have not stopped repeating that what we achieved in Athens Panathinaikos could do at our place," said Jovanovic, who leaves for Liverpool at the end of the season.
"We have to show humility in order to avoid an unpleasant setback. The atmosphere I feel around me makes me scared. I have heard it said we have qualified. That's false.
"The reference point, in terms of reflection, is our first half against Salzburg. We were losing 2-0. That's proof that it can happen to us if we're not careful.
"I don't really want to talk about what will happen in the competition.
"However, if we qualify I have the conviction that we could spring a really big surprise.
"But we're at half-time and we're leading 3-1, those are the facts. We have to proceed as if everything was happening in one leg, with a scoreboard showing 0-0."
Standard have been hit by the news they will be without captain Steven Defour who will be sidelined for up to six weeks after limping out of the first leg.
Pana were left reeling by last week's defeat, especially since Europe was beginning to sit up and take notice of the Greek club following two 3-2 victories over Italian giants Roma in the previous round.
Coach Nikos Nioplias insists his team should be the ones who progress.
"We are better than Standard," he said. "We lost because everything was going wrong at the beginning of the match.
"When you lose a match 3-1, you can't say anything. But we insist, we are better than Standard."
Nioplias blames a packed fixture list for his club's European disappointment and has already admitted he is unlikely to field a full-strength team tomorrow.
He added: "We' re playing tomorrow, Sunday and Wednesday in the cup. It's a very weighty programme which forces us, even if it's abnormal, to sacrifice one competition. That will be our European campaign.
"We know that it will be very difficult to progress to the quarter-finals but if we're going to Liege, it's to try to do so.
"One thing is certain, our mission is very difficult but we're going to do our best."
Loukas Vyntra remains a doubt while Simao is suspended following his stoppage-time dismissal last week.
