The Cobblers preserved their Football League status with a win over Oxford United at a packed Sixfields - but they did it the hard way.
The Us took the lead after just six minutes to leave the home crowd in stunned silence and with grave concerns as Wycombe went in front at Torquay.
But a controversial sending-off for visiting midfielder Ryan Williams turned the tide of the game before a well-taken John Marquis goal restored parity and rising star Ivan Toney put the Cobblers ahead with a header.
Centre-back Mathias Doumbe made it certain with a thumping header and Oxford never returned to the game as a serious force.
The win means Chris Wilder’s men will be playing League football next season and that it is Bristol Rovers, who lost at home to Mansfield to slip into the bottom two on the final day of the campaign, who go down.
James Constable, chasing the goal that would make him Oxford’s all-time leading scorer, had a shot blocked in the first 30 seconds as the hosts made a nervous start to the game.
And they fell behind with just six minutes on the clock when a corner from the right-wing side flicked on by Dave Kitson and was turned beyond Matt Duke by Williams from no more than five yards.
With news emerging of Wycombe’s goal at Torquay and Oxford still on the front foot, the Sixfields crowd was almost completely silent.
The team responded well, though, with Toney bursting clear of the defence and rounding goalkeeper Ryan Clarke only for the covering defenders to force him to place his shot across the goal and against the foot of the right-hand post.
Williams was sent off after 18 minutes but will feel aggrieved about it because it was for no more than a tangle with Ricky Ravenhill after both men had competed for the ball in central midfield.
Without question, it changed the flow of the game because until that point, Oxford were the better side and Williams had been the best player on the pitch.
Chris Hackett struck a shot narrowly over the bar with his less-fancied left foot from 25 yards and then volleyed another over from inside the box.
It felt like an equaliser was coming and so it did, on 29 minutes and with Marquid converting superbly.
Evan Horwood played a long pass to the front line that was flicked into the Millwall man’s strike partner Toney and his first and second touched were excellent to take him away from the covering defenders.
From 15 yards, he tucked a right-footed shot inside Clarke’s left-hand post and the home supporters went wild.
It was a similar distance from which Toney scored the second, glancing home Horwood’s cross past Clarke, who had decided to leave his line and was in no man’s land.
Marquis flicked a Hackett corner goalwards in the final minute of the first half, the ball deflecting away for a corner on the opposite side.
The Millwall man thought he had scored a second when another Hackett corner was blocked by Jake Wright, whose final touch appeared to be not only with his hand but also behind the line.
There was no doubt about the third, a textbook power header by Doumbe, who had only come on as a substitute at half-time, from an inch-perfect Hackett free-kick.
Emile Sinclair almost put the icing on the cake when, with the game being played at testimonial pace, he beat the offside trap and lobbed Clarke only for Wright to sprint back and prevent the goal with a sliding clearance.
This was the second game running in which the team scored three goals, having only achieved that feat on one previous occasion.
They hit form at exactly the right time.
Cobblers: Duke, Tozer, Diamond, Robertson, Horwood, Hackett, Ravenhill, Carter, Morris, Marquis, Toney
Subs: Doumbe (for Robertson 46), Sinclair (for Marquis 62), Dickenson (for Toney 74)
Not used: Snedker, Deegan, McSweeney, Langmead
Oxford: Clarke, Bevans, Hunt, Wright, Newey, Davies, Ruffles, Williams, Rose, Kitson, Constable
Subs: O’Dowda (for Kitson 57), Marsh (for Constable 75)
Not used: Meades, Crocombe, Wroe, Long, Shama
Oxford fans: 1,358