Caretaker boss Dario Gradi felt fatigue played a part in Crewe's home defeat to Chesterfield.
Drew Talbot scored the only goal of the game in the 27th minute to seal a sixth straight victory for the promotion-chasing Spireites.
"The players were tired after having several games in quick succession but they were poor," said Gradi.
"They got behind the ball and defended well against us. Byron Moore was unlucky with his shot that hit the bar but we didn't create too much."
Gradi added: "In the second half we were poor. They sat back and were happy to play on the break and we couldn't get through them. We tried to play into people's feet when I wanted us to go wide."
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