The Terriers go into tomorrow’s clash knowing that victory will leave them seven points clear of the third bottom Eagles.
In a competition as keenly fought as the Premier League, such a gap would be hard to bridge with just seven games remaining.
“If you have to stand up for your football club it’s tomorrow,” said Wagner when asked if he had a message for the home fans in the sell-out crowd.
“This has to be a further step for all of us. The atmosphere has to be extraordinary, something we have never seen before. We can make the gap bigger between Crystal Palace and us.”
With Town’s final quartet of games including clashes with Arsenal, Manchester City and Chelsea, tomorrow’s clash against a fellow relegation candidate has huge importance.
Asked if this was his biggest game as a manager, Wagner replied: “If I say yes, I say it for the next game as well.
“We should not make the mistake of making circumstances bigger than they are.
“In the big games, the players performed. In important moments, they were there, focused on job, desire, fighting spirit and now they have another chance.
“We are focused on the chance to collect a further three points. Tomorrow, it is team spirit and Terriers. We hope we are able to show the team spirit.”
Jonas Lossl has agreed a deal to make his loan switch permanent come the summer.