Two late goals clinched Mansfield's first win in nine games as they triumphed in this basement battle to leave Northampton with the wooden spoon and without a win in eight matches.
The Stags, trailing after 50 seconds to Darryn Stamps' quick fire goal, the fastest in the country on the day, looked to have been frustrated in their search for an equaliser by several fine saves from keeper Glyn Thompson.
But Andy White headed in Liam Lawrence's cross and 13 minutes from time Northampton substitute Luke Chambers fouled Junior Mendes to allow Lawrence to hit the winner from the penalty spot.
Substitute Marco Gabbiadini squandered two clear chances for a late Northampton equaliser and four minutes from time Chris Hargreaves was also denied by Kevin Pilkington's acrobatic save.
The visitors got off to the perfect start when Stamp raced clear to reach Richard Hope's long pass to score inside the first minute.
Mansfield's leaky defence, which had failed to keep a clean sheet in 15 successive games before Stamp's opener, was then torn apart twice more in the opening ten minutes.
Steve Morison fired over from Paul Trollope's free kick and then Paul Harsley's shot bobbled narrowly wide.
But from then on the Stags mounted a determined fight back.
Lawrence almost blasted the home side level with a pile driver which Thompson only saved at the second attempt.
Mendes fired into the side netting, saw another shot well saved by the keeper and later hammered against the bar.
A fluent passing move involving six players ended with White setting up the surging Bobby Hassell only for the fullback's fierce drive to rebound to safety off the busy Thompson.
Mansfield continued to dominate after half-time. Mendes was again thwarted from close range by Thompson who then dived full length to tip away White's low finish.
However, Mansfield finally found the back of the net through White before Lawrence completed the fightback from the spot.