Northampton’s promotion charge suffered a bump in the road as they were beaten 3-0 at struggling Newport.
Omar Bogle's double and a stoppage-time stunner from substitute Charlie McNeill inflicted a first defeat on Northampton since February 18.
The Cobblers were on top throughout the first half but found themselves a goal down at the break.
After Mitch Pinnock, Harvey Lintott and Louis Appere had all gone close for the Cobblers, it was Bogle who scored against the run of play on 43 minutes.
The striker fired in from close range for his 12th of the season after Lee Burge had saved superbly from substitute Declan Drysdale.
County had the chances to extend their lead after the break through Bogle, Calum Kavanagh and James Waite, while Sam Hoskins squandered two opportunities for the visitors.
Bogle settled the contest from the spot in the first minute of time added on and McNeill added a sublime third at the death.
Northampton remain second but are now only a point above fourth-placed Stevenage.