MILLWALL ended a run of six league games without a win as they claimed the three points at Northampton.
Steve Morison almost caught Adam Smith off his line from 40 yards before Lee Gregory put Millwall ahead in the 32nd minute with a smart finish inside the box.
Northampton twice came close to finding an equaliser in the first five minutes of the second half, but Jordan Archer got down to save Sam Hoskins' shot before Jak McCourt's drive hit the crossbar.
Minutes later McCourt was sent off when he picked up his second yellow card for a foul on Fred Onyedinma.
The Lions went 2-0 up in the 60th minute, Calum Butcher scoring his first goal for the club since his summer move from Burton.
Paul Anderson fizzed a shot over the crossbar before moments later another effort from the midfielder was deflected just off target.
Northampton pulled a goal back in the 80th minute when substitute Marc Richards headed past Archer from eight yards. But Morison made sure of the win when he lifted the ball over Smith a minute from time.
Neil Harris had seen something he liked in Millwall's formation in the second half of the EFL Trophy win over Gillingham. Ben Thompson started on the left of midfield, with Butcher making just his third league start since his August move from Burton.
That often meant Thompson moved inside, leaving Shaun Williams to track back to help out Joe Martin, but Northampton struggled to create anything of note in the first half.
If Millwall's aim was to make this contest a scrappy one, the audible frustration of the home crowd told of the away side's success.
Northampton's McCourt was booked after just 12 seconds, and that set the tone in a game too often punctuated by free-kicks. There were 19 in the first half with both sides feeling aggrieved by Ben Toner's handling of the game.
Millwall had fallen behind to the first goal in their last seven league games, but they ended that run and it was a typically composed finish from Gregory. The striker was more alert than Zander Diamond when Williams pumped a ball forward and though Gregory was slightly clipped by the defender he opted to stay on his feet to finish to the far corner past the advancing Smith. It was Gregory's fourth goal of the season and first from play – and also the only shot on goal in the opening 45 minutes.
Immediately before that move Martin did well to head away JJ Hooper's dangerous ball into the box epitomising that defensive aggression Harris has been reminding his players about. Tony Craig and Byron Webster were also relishing a physical confrontation, while one Williams tackle on John-Joe O'Toole left the midfielder on the turf and slow to get to his feet. It all added up to the basics that had had been missing through that run of four successive league defeats.
But that could have all been undone had McCourt's rasping shot from outside the box been a couple of inches lower. Then McCourt undid all his good work when he needlessly fouled Onyedinma on the right touchline.
Without that cover in midfield Butcher felt more confident to get forward, but Brendan Moloney probably should have cleared when Gregory found his team-mate just outside the box. The defender didn't, instead falling over to allow Butcher to pick his spot low to the far corner.
The game was far more open than it had been before the break and Millwall had to be careful as Anderson was twice allowed to shoot from outside the box. With Northampton pushing more players forward, Gregory also found more space and he went close to getting his second of the game when he aimed a left-footed effort to the far corner that was deflected wide.
Northampton found a way back into the game with 10 minutes left when two of their substitutes combined. Sam Hoskins was given too much room on the right to cross, and Harris will wonder why striker Richards was left free in the centre of the penalty area to direct his header past Archer.
But any doubts that Millwall's winless run would go on were ended when Morison scored his eighth goal of the season. And he enjoyed the moment against one of his former clubs, pointing to the name on the back of his shirt has he celebrated.
Image source: ©Charlie Compitus