Gary Caldwell was furious his side failed to make the most of their lead against Sheffield Wednesday as they were knocked out of the Carabao Cup.
The Owls ran riot at Hillsborough in a dominant 4-1 victory, but not before the Spireites went ahead.
Kristian Dennis scored from the spot, before Gary Hooper, Steven Fletcher, Barry Bannan and Sam Hutchinson all netted for the hosts.
“We should have held onto our lead for longer, no doubt about it,” admitted Caldwell, who took his fury out on a water bottle after his side went behind.
“It’s disappointing that we couldn’t even see it out until half time and by then we were actually behind.
“There are improvements to be made, as there always are in football.”
Despite the scoreline the Spireites did have their chances.
Last season Caldwell’s men struggled to even forge out meaningful chances against League One opposition, so that is a step in the right direction.
Carlos Carvalhal’s Wednesday are brimming with talent across the pitch and that is something that needs to be remembered in wake of this defeat - Chesterfield’s 11th in a row in the competition.
Caldwell added: “We knew it was going to be a difficult game.
“Sheffield Wednesday are a quality side full of international players.
“I think we were better than we were on Saturday in a few aspects and we have to remember we aren’t facing this quality every week.”