Full-time from Sixfields StadiumMillwall returned to winning ways in League One with an excellent awayday victory at high-flying Northampton thanks to goals from Lee Gregory, Calum Butcher and Steve Morison .
Gregory fired The Lions into a first-half lead and midfielder Butcher put Neil Harris' side 2-0 ahead on 59 minutes, four minutes after Northampton's Jak McCourt had been dismissed for a second bookable offence.
Harris made two changes to the side that started in the last League game at Walsall, bringing in midfielders Butcher and Ben Thompson for Jimmy Abdou and Shane Ferguson, both of whom dropped to the bench.
The manager had spoken before the match of his belief that the extra time spent on the training pitch following the international break could prove to be of benefit to his squad - and his optimism was proved right with an important, impressive, victory following a run of six League games without a win.
There were just eight seconds on the clock when Northampton's McCourt found himself in referee Ben Toner's book for a crude challenge on Fred Onyedinma. McCourt was a busy man in the opening exchanges and nearly gave Northampton the lead after two minutes when he was played in by Brendan Moloney, but lashed his shot narrowly over from 16 yards.
Midfielder Shaun Williams sent a curling free-kick straight into the hands of home keeper Adam Smith and from a near-identical position at the other end, Alex Revell fizzed an effort a whisker over the bar barely 60 seconds later.
The Lions made the all-important breakthrough 13 minutes before the break when Gregory picked up a long forward pass from Williams, managed to keep his feet despite having his shirt tugged, and neatly tucked the ball into the far corner beyond the reach of Smith.
JJ Hooper had a great chance to level but contrived to fire wildly off target after Harry Beautyman had slipped the ball through to his team-mate in space.
The Lions needed no further incentive to push forward and took full advantage of their numerical superiority just six minutes later. Butcher did well to keep possession high up the field and strolled into the penalty area before coolly dispatching a low angled shot beyond the keeper's reach.
His celebrations with the jubilant travelling fans behind the goal earned Millwall's recent recruit a booking after he was deemed to have 'over-celebrated' his first goal for the club.
Morison and then Gregory could have made it 3-0 with efforts that flashed off-target as The Lions looked to put the result out of reach.
However the best laid plans often don't work out, and Northampton ensured that there was a grandstand finale when, with 10 minutes remaining sub Richards - presented with a framed shirt before the game to commemorate his 50th goal for Northampton - got on the end of a Hoskins cross and sent a header into the back of the net beyond Archer's reach.
It was heart-in-mouth stuff as the action swung from end to end, but when a cool head and clinical finish were needed, there was Morison to latch onto a forward pass and send a superb lob over the on-rushing Smith to put the seal on a good afternoon's work by The Lions.
Sending off: McCourt (54mins)
Scorer: Richards (80mins)
Bookings: Williams (27mins), Martin (86mins)
Scorers Gregory (31mins), Butcher (59mins), Morison (88mins)
Att: 6,908 (away 1,019)