Two goals from long balls consigned the Cobblers to a 2-0 defeat at a windswept Gillingham as they slipped out of the npower League Two top three.
Cody McDonald scored after three minutes after a Lee Nicholls error, and Myles Weston put the seal on the win with a classy finish eight minutes from time.
The defeat, combined with the point Burton Albion took from a 1-1 draw at Oxford United, means the Brewers replace Northampton in the automatic promotion places.
In what was an awful game played in restricting conditions - horizontal wind with constant drizzle thrown in for good measure - neither side looked to play any real football, instead opting for a direct approach built on players only ever taking one or two touches.
The wind made a swirling impact on the game after only three minutes when Matt Fish’s long ball from right-back sailed over Nicholls, whose positioning was bad, leaving McDonald a free run at goal.
He made no mistake, tapping into the unguarded net from no more than a yard with the visiting defence appealing in vain for an offside.
A similarly swirling kick from Nicholls’ hands creating problems at the other end with the defence misreading it but Ben Harding failing to put enough on a header that Stuart Nelson comfortably collected.
Harding then saw a shot smothered by two covering defenders after a Luke Guttridge shot from the edge of the box had been pushed away by Nelson.
It was as good as it got for the Cobblers, who offered very little as an attacking force in the second half and watched on as it came to a conclusion with Myles Weston scoring the home side’s second goal.
A long goal kick found its way all the way to Weston 25 yards from goal, the forward taking a touch and advancing past Clarke Carlisle before placing a shot perfectly inside Nicholls’ left-hand post.
It was enough to bring a conclusion to a desperately scrappy game in which neither side looked like promotion material and which will also reopen the debate about Northampton’s ability to deal with long balls behind their central defenders.
It remains their Achilles heel.
Along, of course, with their performances away from home.
Gillingham: Nelson, Fish, Barrett, Legge, Martin, Lee, Gregory, Frampton, Weston, Burton, McDonald
Subs: Whelpdale (for McDonald 83), Kedwell (for Weston 87), Allen (for Lee 90)
Not used: Forecast, Davies, Strevens, Birchall
Cobblers: Nicholls, Tozer, Langmead, Carlisle, Widdowson, Hackett, Guttridge, Hornby, Harding, Robinson, Platt
Subs: Akinfenwa (for Guttridge 63), Demontagnac (for Robinson 80)
Not used: Snedker, Johnson, Oyeleke, Wilson, Moult
Cobblers fans: 183