Spireites captain Sam Morsy reflected on a tough night for his side as they lost 3-0 away at Doncaster Rovers on Tuesday night.
The game had been level at the break with both sides creating but not taking chances during the first 45 minutes.
However, six minutes into the second period a Dan Jones handball gave Rovers the chance to open the scoring from the spot, and after Nathan Tyson had taken the opportunity at the second attempt Chesterfield were unable to get themselves back into the game.
Morsy explained that the concession changed the make-up of the match: "We gave them a penalty that we never should have given away and then as we were chasing the game they scored one of the break and scored another at the end.
"We know it's not good enough and we know we have to improve. We're letting the manager, coaches, fans and ourselves down."
The defeat was the third in a row for the Spireites, and with Swindon Town visiting the Proact on Saturday, Morsy knows that it's time for the squad to stand up and be counted.
"We know that we have to put a run together and get going again," he said. "It happened to us earlier in the season and we have to stick together, stay strong and do the same thing.
"Anybody can beat anybody as we can see in this league so it's about application and we need to give our all."