Exeter City manager Gary Caldwell says some of his fringe players missed the chance to stake a claim in his side after their 2-1 loss to Leyton Orient.
City had seven front line players missing either through injury or international call-ups.
But the Grecians conceded a stoppage-time goal as they fell from the top of League One after the loss.
"The players that came in, that opportunity was there for them and some of them didn't take it," Caldwell said.
"That's football, you have to be ready every single Saturday for a game of football.
"We are a team that's going to have to rotate players and use a small squad, so these players have to learn from that missed opportunity, and that will come again at some point this season, so hopefully they can grab it the next time," he told BBC Radio Devon.
Despite a wonderful long-range goal from Demetri Mitchell to give Exeter the lead they could not hold on as Orient levelled through Joe Piggott soon after before Ruel Sotiriou's 92nd-minute winner.
It was a rare low moment for Exeter this season, who had won four of their opening six games to top the League One table and reached the third round of the Carabao Cup for the first time since the 1989-90 season.
"Right from the start of the game we didn't get going at any point," Caldwell added.
"We had a magical moment in the second half with Demi's goal, it was an outstanding finish, but even that couldn't get the team going and shake them out of the performance we were in.
"We didn't put any passes together, we didn't have any energy to our play, we didn't penetrate the last line enough and ask enough questions of Leyton Orient defensively.
"But I've said to the players I can't get angry with them, they gave a massive effort at the start of this season to be in the third round of the cup for the first time in 30-odd years, to be at the top of this league after six games is a huge achievement.
"But this is a lesson that you have to keep going, you can't rest on your laurels in football, you have to keep driving forward and keep pushing, and we have to take this as a bump in the road and recover from it."