While Notts County edged closer to Second Division safety through this result they made Huddersfield Town relegation even more probable.
Huddersfield could scarcely have offered more to caretaker manager Mel Machin and were distraught at the end to have gone down to an injury-time decider from the penalty spot.
Huddersfield were fully deserving of Andy Booth's 19th minute goal having twice gone close in the earlier proceedings.
Nat Brown's right-wing cross was deflected by defender Craig Ireland into the path of Booth at the back post and he headed home with ease.
A defensive mistake by Jason Gavin let in Paul Heffernan for a headed equaliser before Martin Smith restored Town's advantage before the interval from a free-kick.
Huddersfield deserved to be in the lead at the interval but in a scrappier second half found Notts in better form, if only fitfully so.
Notts were hauled level with the first of two ice cool finishes from the penalty spot by leading scorer Mark Stallard, who was tripped by Brown in the area to end his delightful run.
Stallard chipped the ball wide of Phil Senior and for a long time that looked like being the end of the scoring. Then in a very dramatic finale Adie Moses handled, referee Scott Matthieson pointed to the spot for the second time and Stallard netted again.
Huddersfield could scarcely believe what had happened to them and threw everything at the Notts defence in the last frantic moments.
But Notts held firm with 20-year-old Irish debutant goalkeeper Saul Deeney making a good save on top of his earlier good work.
Deeney was not to blame for either concession in the first half.
Notts fielded a second debutant in on-loan Patrick McCarthy from Manchester City and he had one of the game's stiffest tasks in seeking to contain Town dangerman Danny Schofield, among those who did not deserve to be on the losing side.