The 53-year-old Hungarian, whose team have lost all four of their Group E matches in their debut Champions League season, said: "If we even draw against Liverpool, it will be the greatest result in our club's history."
Liverpool must win in the Ferenc Puskas Stadium and pray that Lyon win or draw away to Fiorentina, and only such a combination of results would leave them with any chance of qualifying for the last 16. A draw in Hungary would end Liverpool's hopes of reaching the last 16.
Herczeg says: "This game is easy for Liverpool. They have to win, nothing else will do.
"We intend making their task as difficult as possible, but whether that is good enough we will only know after the match."
The Champions League has been a daunting experience for the Hungarian champions, who entered the competition full of confidence and enthusiasm, carrying their country's dreams on their shoulders.
The experience has been less rewarding than they had hoped. They lost 1-0 at Liverpool in their first match, and have since been beaten 4-0 by Lyon, and then 4-3 and 5-2 by Fiorentina.
Herczeg's side are currently sixth in their domestic league, with plenty of work to do if they are qualify for next season's European elite tournament.
The coach said: "This has been a great experience. We have learned so much. In particular that you just cannot lose the ball at this level.
"If you do, much better sides will always punish you by scoring. Who do I think are the best two in the group? It's hardly for me to say, all three of our rivals are really great clubs and I cannot choose between them.
"This match with Liverpool will be our last at home in the Champions League until we qualify again.
"Our aim now is to show our best. We were confident when we started this journey, and we still retain that confidence, but it has been a tough way to learn.
"But we still aim to win our first point in the group, and we hope to do that against Liverpool. Whether our best will be good enough, we must wait and see."
Midfielder Peter Szakaly underlined the difference which Debrecen have found between domestic and European football.
He said: "In the Hungarian league we know that with five or six players at their best, we will win. In Europe all 11 must be at the very best all the time.
"We have learnt in the glaring spotlight that follows the Champions League around."
Debrecen have lost 27-year-old Hungarian international Leandro with a hamstring injury. Gergely Rudolf is expected to deputise.
Debrecen are likely to field nine of the side that lost at Anfield in September.