The youth team went down to a 3-1 defeat at home to Mansfield Town on Saturday.
Zac Walker put the young Spireites ahead in the first half but Mansfield hit back to win.
Coach Miguel Llera explained that the game changed after the interval. He said: "We managed the game really well in the first half and scored when Javanne Smith made a good run and played the ball to Zac Walker, who produced a good finish.
"We had to replace Dylan Wharton in goal with Kurtis England at half time and then Jack Holmes also went off injured early in the second half.
"They posed more of a physical threat in the second half and scored two good goals from outside the area.
"They were playing long balls and using long throws and we didn't deal with that. We couldn't cope with the physicality."
Spireites: Wharton (England h/t), Emery, Gibson, Render, Wild, Bradbury, Howard, Walker, Smith, Holmes (Turner 50), Fuertado
Unused substitutes: Papworth, Tansley & Barrass