Martin Devaney hit the winner on his return to the starting line-up after Richard Forsyth had held his nerve to score two penalties.
Northampton raced into a controversial two-goal lead in the first half, with Lawrie Dudfield bagging a brace. The first came after Shane Higgs came to claim a cross and appeared to be fouled, Dudfield headed the ball in, but no-one seemed to expect the goal to be given.
As the Northampton players began to celebrate, it soon became apparent that the referee had allowed the 23rd minute goal to stand, much to the frustration of the home supporters.
Dudfield’s second came after Mike Duff was dispossessed as he dribbled the ball out of defence, leaving a gaping hole that the former Hull striker exposed and supplied a neat finish past Shane Higgs.
Starting the second half two goals behind, Cheltenham attacked with purpose and veteran forward Bob Taylor scored his third in two games after 56 minute, curling home from just inside the box.
Cheltenham went in search of an equaliser, but were dealt a blow when the referee awarded the Cobblers a penalty for a challenge on Martin Smith by Bertrand Cozic. Smith beat Higgs to make it 3-1, but it was then that the real drama unfolded.
Bobby Gould threw on Richard Forsyth, Paul Brayson and Lee Howells, Howells making his first league appearance since March 2002. A push on Taylor resulted in Forsyth’s first spot-kick, which was despatched with aplomb.
There was an electric atmosphere inside the ground in front of the first 5,000-plus crowd of the season and as the Robins pressed for another leveller, Jamie Victory was chopped down in the area by Oli Burgess after good work from Fyfe and Brayson.
Forsyth stepped up again and beat Glyn Thompson low to his right, but as the ground erupted, the referee had spotted a player encroaching into the area so Forsyth had to do it again under immense pressure.
As the game entered the final minute of the 90, the former Peterborough midfielder made no mistake and it was all square at 3-3.
Gould’s men were not content with a point and continued to attack. In the 94th minute, Devaney snatched a memorable winner to cap an enthralling match. The winger, recalled in place of Grant McCann who is on international duty, capitalised on a defensive mix up between Paul Reid and Peter Clark, thundering a shot past Thompson to spark scenes of wild celebration.
The final whistle was blown seconds later and ‘the entertainers’ had done it again, against a side tipped to be major contenders for promotion this season.