Grant Black wants to see a response from his players when they travel to Carlton Town on Saturday.
His message comes following Belper Town's "uncharacteristic" display in the 2-2 draw at home to Spalding United.
The Nailers twice came from behind through Phil Watt and a late Alex Peterson leveller to earn a share of the spoils.
But it was a performance - in front of a bumper 429 crowd at the Raygar Stadium - which surprised Black.
"It was an unexpected performance," he told the Belper News. "We were really shell-shocked by it because we've been playing so well.
"We've had good shape, good work ethic and everyone knows their jobs - that's what makes us difficult to play against.
"On Saturday we were just completely opposite.
"We had no shape, we were flat-footed, second to things, physically we were weak.
"It was a really poor performance and the worst we've seen with the ball since we've been here.
"At the level the lads are playing at, sometimes it does happen but key things weren't there on Saturday.
"We changed things before the game because we had a report on Spalding that said they had a lot of pace up top.
"We didn't play to that game plan and it was disappointing.
"The lads were told that at the end of the game and I'll be looking for a massive response this Saturday."
Despite the draw, Belper extended their unbeaten run to eight games in the league and sit fourth having lost just twice all season.
"We're eight games unbeaten on the back of a 16-game unbeaten run so the consistency has been there," said Black.
"Whether we switched off or what, I'm not sure, but it was an uncharacteristic performance which shocked us because we've been doing well.
"We had choice words with the players both individually and as a group.
"That [performance] can happen once but if it happens again then there'll be big changes made to the playing squad to get us where we want to be."
On Saturday they face a Carlton side placed just outside the play-off picture and four points behind the Nailers.
"We've had a run of games against teams who have been up there.
"Spalding are very strong away from home but if we had performed the way we can then we would have won that game.
"Carlton are strong at home and doing really well.
"If we perform like we did this weekend then we'll get zero points.
“If we get back to what we're good at then I think we've got the potential to come away with three points,” added Black.