Paul Cook admits that the defeat to Rotherham last weekend was a blow for everybody at the club.
The Spireites struggled to get a foot-hold in the game and went down to a Johnny Mullins header mid-way through the second-half.
Cook acknowledged that the performance was not up to scratch and is determined not to let down supporters like that again.
Speaking ahead of the Gillingham game, he said: “It was huge disappointment for everyone at the club.
“I think we’re all entrusted with that responsibility to make our public happy in Chesterfield, and we disappointed them badly last Saturday. We know that.
“Sometimes when you self-reflect and you look back and you think to yourself, ‘could we have done more? Unfortunately we can’t go back in time and play that game again.”
Saturday sees the visit of league leader Gillingham. The Gills have a very strong record on the road, racking up 10 wins and just one defeat.
Although the manager is expecting a tough game at the weekend, he is looking for his side to affect the game in a positive manner.
He said: “They’re going to be very direct. It won’t be a pretty football game on Saturday.
“We must be mindful and strong enough to stand up to what they offer. Then we’ve got to go and affect the game well.
“We’ve got to go and play when we can and we’ve got to score goals.
“Certainly our home support, like our away support, is fantastic but we must give the supporters something to shout about early on in the game. We can’t do to them what we did last Saturday”
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