Chris Hackett’s first goal of the season gave the Cobblers a second successive win, at the expense of Southend United at Sixfields.
Hackett and Mathias Doumbe - who doubled his Town goal tally with a second headed effort in four days - were on target in a 2-1 win that lifts the side off the foot of Sky Bet League Two.
It is the first time the team has achieved back-to-back victories this season and although the gap to safety remains five points they are now in good form and starting to build momentum.
Gregor Robertson came in for Joe Widdowson at left-back in the team’s only change from the side that beat Hartlepool and within six minutes they were in front.
Brennan Dickenson fizzed in a low cross that was put behind for a corner by John White and Hackett delivered a whipped ball in that Doumbe met with timing and ferocity at the back post.
Dickenson got his head to another superbly-placed Hackett dead ball moments afterwards but could not divert it goalwards.
It was a frantic start to the game and after only 16 minutes the visitors had equalised, Michael Timlin making an untracked run from central midfield to beat Town’s offside trap before finishing calmly under Duke.
It was part of a superb Southend response to falling a goal behind and after it they began to dominate possession and territory.
Dickenson spurned a good chance to score against the run of play, though, when another Hackett free-kick was turned back into the danger zone from Zander Diamond.
From no more than 10 yards, the on-loan Brighton winger blazed horribly high of the target.
Then a Southend counter-attack almost undid the home defence but Barry Corr’s weak shot was straight at Duke.
The second half was as wide open as the first and the Cobblers retook the lead 13 minutes into it with a goal created expertly by substitute Alan Connell moments after his introduction.
The forward killed an aerial ball stone dead and threaded a dead-weight pass down the right-hand touchline to Emile Sinclair, who used his strength and speed to get beyond Ben Coker and pick out a pass to Hackett.
The winger, just as Dickenson did in the previous game, arrived in the centre-forward position and powered the ball past Daniel Bentley in the Southend goal despite being under pressure from a defender.
Hackett had the ball in the net for a second time shortly afterwards but the header, from a chipped Connell pass, was ruled out for offside.
They had a lucky escape, though, when Leon McSweeney fouled Anthony Straker after he had found space down the inside-left channel.
The tackle looked like it was in the box but the referee blew for a free-kick right on the 18-yard line and Freddy Eastwood, on as a substitute, drilled it into the wall.
Cobblers: Duke, McSweeney, Diamond, Doumbe, Robertson, Hackett, Ravenhill, Carter, Dickenson, Marquis, Sinclair
Subs: Morris (for Dickenson 54), Connell (for Marquis 54), Deegan (for Sinclair 86)
Not used: Tozer, Snedker, Toney, German
Southend: Bentley, White, Phillips, Coker, Atkinson, Timlin, Laird, Leonard, Straker, Barnard, Corr
Subs: Eastwood (for Barnard 57), Hurst (for Laird 73), Williams (for Straker 86)
Not used: Smith, Payne, Banton, Gornis
Away fans: 377