Torquay manager Chris Hargreaves admitted goalkeeper Michael Poke's mistake had been the turning point in a 3-1 loss to Chesterfield.
Hargreaves's team looked in control and on course for a vital win after Shamir Goodwin raced clear down the right in the 50th minute to fire an unstoppable shot into the roof of the net from 15 yards.
Chesterfield were finding it hard to break down an organised Torquay side but six minutes later Poke's attempted clearance hit Krystian Pearce in the back and Eoin Doyle ran through to equalise.
Torquay should have regained the lead after Goodwin hit a post in the 78th minute but substitute Conor Wilkinson put the rebound wide and two minutes later, Liam Cooper put Jay O'Shea in to score from the edge of the box.
O'Shea added another in stoppage time but Hargreaves knew the damage had already been done.
"We contained a really good side and scored a fantastic goal but we made some decisions that have cost us and conceded a goal at a time we were comfortable," he said.
"Let's just say it was an unusual goal to concede. We've given them a goal which is hard to take because it's hard enough to score goals and we've scored a fantastic one and they've scored an awful one.
"It was a pivotal moment but Pokey has been great for this club and he's made a mistake that we are disappointed with but it's something he's probably not done before and will never do again.
"It's frustrating because it's hard to score a goal in football but that's life, we all make errors and we have to dust ourselves off and recover quickly because there's no point in laying on the floor because no one cares about Torquay United apart from us."