Peter Leven's 89th-minute free-kick revived Chesterfield's promotion hopes and condemned fellow hopefuls Rochdale to a fifth successive home defeat.
Rochdale were the stronger team in the first half with Kallum Higginbotham and Lee Thorpe going close with headers.

But Chesterfield nearly scored when Jack Lester's first-time shot brought a good save from James Spencer.

The visitors snatched a late winner when Leven drove home from just outside the area with one minute remaining.