Adam Gusterson is demanding a reaction from his players after what he called the worst performance since returning to the club.
The Magpies enjoyed a good FA Cup win at Spalding a week ago, but two days later slumped to a 2-1 home defeat in the league against Soham Town Rangers.
Today, Dereham travel to Essex to face Great Wakering Rovers, and Gusterson - who, with Olly Willis, took over in January - expects better.
"Monday was the worst performance we have had since we have come to the club," he said. "We were really flat and deserved nothing from the game. I do believe that three games in five days for a team at our level is a lot to expect and maybe on reflection that had a factor in our energy levels and tempo not being at the usual levels, but it's the first time I have felt a team has outworked us and that can't happen again."
Great Wakering are seventh, after winning won two of their opening three league games, while Dereham are 17th, with two points.
"We now have a very big game on Saturday against Great Wakering Rovers who have started well," added Gusterson.
"We'll be looking for a reaction and I have confidence in our lads that we will get the response we want. A win will change the picture significantly and we could then look at our start with a bit more satisfaction."
Dereham will be without Adam Smith and Ryan Crisp and Rhys Logan will face late fitness tests. David Hinton and Matt Castellan make a welcome return both having missed the Soham Town Rangers game.
The consolation from the holiday weekend was the 4-2 FA Cup win in Lincolnshire, which has helped boost the coffers.
"It was a great win for the club and the prize money makes a significant difference to any club around our level," added Gusterson.
"To guarantee £4,500 from one result shows just how impactful a good cup run.
"We have a tough draw against Needham Market but we are at home and we need our supporters to turn out in their numbers to help us again as they did at Spalding United."
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