For the third league game running Northampton both failed to win and had a man sent off as they were beaten 3-1 by Millwall on a wretched afternoon at Sixfields.
The Cobblers struggled to cope with Millwall's physical and direct approach throughout as the visitors took advantage of some poor defending as well as Jak McCourt's red card to walk away with the points.
Both the game and Northampton struggled to ever get going in the first-half, especially after Lee Gregory's 32nd minute opener put the away side in front.
Town upped the ante after half-time and improved markedly but their chances of getting anything out of the game were dealt a significant blow when McCourt saw red for a second yellow card.
Calum Butcher then seemed to put the result beyond doubt when doubling Millwall's lead on the hour-mark but, to their credit, Northampton never gave up and pulled one back through Marc Richards' header.
The home side huffed and puffed and gave their all in the 10 minutes that remained but there was to be no way back and their hopes were finally extinguished when Millwall wrapped up the points through Steve Morrison's late third.
It was a highly frustration afternoon for all those at Sixfields, made all the more difficult by the referee's insistence on constantly blowing his whistle and awarding free-kicks which never allowed the game to flow.
But, in truth, Northampton were at times bullied by their visitors and this was a harsh lesson in how to manage to a game and take your chances when they come along, something which Millwall did to great effect, with this result dropping Cobblers down to ninth in League One.
And to add to their misery, Northampton will now be without both Matty Taylor and McCourt for Tuesday's trip to rivals Peterborough.
Harry Beautyman was chosen as the man to replace Taylor, who was serving the first of his three-match suspension, in the only change to Rob Page's last starting XI.
McCourt was at the centre of things early on, finding himself in the referee's book inside just 14 seconds for a strong challenge on Fred Onyedinma before he then whizzed a 20-yard shot narrowly over Jordan Archer's crossbar.
At the other end, Steve Morrison went close to a spectacular opener when sweetly connecting with a 40-yard volley that dipped over Adam Smith and onto the roof of the net, but that was all either side had to shout about in a scrappy, disjointed opening quarter.
Neither team were able to grapple control and really assert themselves in an error-strewn first-half that had quickly become dominated by constant cheap fouls and half openings.
Of those half chances, Morrison lifted over from a tight angle and Shaun Williams sent a tame free-kick too close to Smith while from another set-piece, Alex Revell went for power but blazed well over.
A goal seemed unlikely given the pattern of play but just after the half-hour mark, the visitors struck a bolt from the blue.
It all started from a Northampton attack as Millwall cleared the danger and what appeared a harmless long ball down field was latched onto by Gregory who out-paced Zander Diamond and delicately shot beyond Smith and into the bottom corner.
JJ Hooper wasted an opportunity to hit straight back for the Cobblers as he selfishly blazed high and wide with team-mates better placed before John-Joe O'Toole's wayward pass ended a promising breakaway on the brink of half-time which rather summed up a poor opening 45 minutes.
A change in both personnel and shape to 4-4-2 at the break breathed new life into Northampton after the restart as substitute Sam Hoskins skipped past two defenders and forced the first real save of the game with Archer down quickly to beat away the shot.
Archer had to be at his best again moments later when tipping McCourt's 30-yard thunderbolt onto the underside of the crossbar and away from danger, but all Town's momentum was then undone by a moment of madness.
McCourt, already on a booking, launched into a needless, late challenge on Onyedinma and the referee had no choice but to issue a second yellow card and send the Northampton man for an early bath.
And the home side's frustration only grew on the hour-mark when Millwall made it 2-0.
Brendan Moloney was robbed of possession on the edge of his own penalty area and Butcher easily beat the onrushing Smith to put his side in total control.
That left Northampton with a mountain to climb but they didn't go down without a fight as Paul Anderson twice sent rasping shots just over the crossbar, while Gregory did likewise for the visitors in a helter-skelter end to the game.
The Cobblers were refusing to go away quietly and continued to attack in numbers, and their persistence paid off with 10 minutes remaining when the excellent Hoskins teed up Richards who clinically headed into the bottom corner.
That gave Northampton renewed belief and back they came for more, however all their pressure failed to result in clear-cut chances.
And the game was put to bed in the final minute of normal time when more hesitation in the Cobblers defence from another long ball allowed Morrison to nip in and coolly loft over a stranded Smith, wrapping up all three points for the visitors.
Cobblers: Smith, Moloney, Diamond, Nyatanga, Buchanan, O'Toole, McCourt, Anderson (Gorre 85), Beautyman (Hoskins 45), Hooper (Richards 65), Revell
Subs not used: Cornell, Zakuani, Byrom, Potter
Millwall: Archer, Romeo, Webster, Craig, Martin, Onyedinma (Ferguson 64), Williams, Thompson (Worrall 78), Butcher, Morison, Gregory (Abdou 84)
Subs not used: Nelson, Pavey, Philpot, King
Referee: Ben Toner