The youth team saw their unbeaten start to 2018 come to an end on Saturday, as they lost 3-1 at home to Grimsby Town in the EFL Youth Alliance North East.
Miguel Llera's side had previously won three and drew one of their league fixtures so far this year, while during that time they'd also progressed to the final of the Derbyshire Senior Challenge Cup.
Saturday's clash was their first in a month, following the recent bad weather, and was switched to a 3G surface at St George's Park Sheffield Graves, due to a waterlogged pitch.
The visitors took a 1-0 lead in to the interval, before doubling their advantage in the second half. Luke Rawson then capitalised on a defensive lapse, to give the Spireites hope, before the Mariners wrapped up the win in the closing stages.
The youth team are next in action on Friday, when they take on Burton Albion at St George's Park Sheffield Graves, 11am.
Chesterfield XI vs Grimsby: Marris, Emery (Walker 46'), Render, Hand, Sharman, Holmes, Foster (Smith 71'), Ofoegbu, Rawson, Howard, Russ (Bradbury 87').
Substitutes not used: Jones (gk), Walmsley.