Truro boss Lee Hodges said his side were "not at the races" in their 1-0 defeat by fellow strugglers Maidenhead in the Blue Square Bet South.
The home defeat leaves the White Tigers 10 points from their nearest rivals as the season nears the halfway mark.
"It wasn't meant to be today. We're absolutely devastated," he told BBC Radio Cornwall.
"We could have earned a draw at best. I don't think we deserved to win it. We weren't at the races today."
The only goal of the game came in the second half when Alex Wall netted for the visitors.
"Luke [McCormick] made a couple of wonderful saves to keep us in the game," Hodges added.
"But their keeper pulled off a couple too so it's disappointing we've got nothing from the game.
"It would've been nice going into the Christmas period with double figures and a seven-point gap, but we're further adrift now."