Chesterfield manager Paul Cook believed his side looked the more likely to go on and claim all three points at Home Park after Ritchie Humphreys had brought the visitors level.
Reuben Reid’s second, just moments after the Spireites had drawn level, proved to be the game’s winning goal on Tuesday night as Plymouth moved into the play-off spots.
But Cook said there only looked one team in it at that point. He said: “We’re very disappointed because in the second half we never felt like we were going to lose the game. We were in the ascendancy. It was a question of if we could score, when we could score, could we get the next one?”
The defeat to Plymouth, managed by former Chesterfield boss John Sheridan, saw Cook’s side slip to second with Rochdale overcoming Northampton Town.
Cook added: “We know there will be bumps and bruises along the way.
“It’s a promotion campaign that we’re on, it doesn’t mean we finish with promotion or finish in the play-offs, it means we must finish the season as strongly as possible.”