John Sheridan says players like Alex Kiwomya must keep working hard, because they will be needed by Chesterfield before the season is done.
The on-loan Doncaster Rovers forward was left out of the last two match day squads.
While Rovers boss Grant McCann will obviously want his player to develop by playing games at the Proact, Sheridan believes his opposite number will trust his judgement on the 22-year-old.
"I spoke to Grant about Alex, briefly, when I was speaking about Alfie (Beestin).
"Obviously Alex came in before I came in.
"I think Grant will trust my judgement and if I'm not playing Alex he needs to do better and he needs to work harder to try and get in the team."
Sheridan, who revealed that Kiwomya was on the scoresheet in this week's friendly at York, has no problem telling players exactly why they're not involved in competitive fixtures.
"He did okay in the game behind closed doors (this week), worked hard and scored a good goal," said Sheridan.
"He's fighting for a place in the side. I'm leaving some good players out.
"I try to be as honest as I can when I leave people off the bench and they don't travel, try to explain if I need a bit more.
"He needs to just keep working hard."
The good news for all parties is that the door to the first team remains open to the pacy attacker.
Sheridan insists that Kiwomya and the other players currently not figuring in what has become a winning team, can still contribute in the battle to avoid relegation.
"I'm going to need them, things will turn up where I'll need them," he said.
"This is the reason I'm trying to get a game every week for the lads who aren't playing.
"Hopefully they'll be ready and they'll want to help when they're needed."