Grimsby Town lost at home for the first time in five games as play-off-chasing Northampton Town won at Blundell Park.
The visitors made the better start and were ahead within 10 minutes as captain Charlie Goode opened the scoring.
Striker Callum Morton doubled their lead but the Mariners created chances and showed enough to suggest they were by no means out of the game at half-time.
But Town were unable to make a breakthrouogh and insteead, it was left to Morton to seal the points for the away side with his second goal of the game.
Six changes were made to the Grimsby starting XI after the midweek home win against Newport, with goalkeepr Sam Russell among those to come in as regular stopper James McKeown was named on the bench.
Luke Hendrie, Ludvig Ohman, Anthony Glennon, Elliot Grandin and Billy Clarke were the others to come back into the team.
Russell started in goal, with Hendrie, Ohman, Luke Waterfall and Glennon forming the defence.
Grandin was joined in midfield by Harry Clifton and Josh Benson, with Clarke, James Hanson and James Tilley in attack.
McKeown was joined among the substitutes by Bradley Garmston, Matt Green, Elliott Whitehouse, Ahkeem Rose, Charles Vernam and Elliott Hewitt.
Northampton began the day in the final play-off position in League Two but on a poor run of form which had already seen them lose four times in February, including a midweek defeat by Cheltenham Town.
The visitors started on the front foot, with a series of long throw-ins sent into the Town penalty area by Goode.
Good play by winger Mark Marshall down the right on seven minutes led to Sam Hoskins crossing but the offside flag went up against striker Callum Morton.
The away side won the first corner of the game two minutes later and from it, they eventually took the lead. The danger looked to have passed when the low ball from the flag was brought clear but Town lost possession and after some pinball in and around the box, GOODE volleyed home from 12 yards.
A shot by Clifton was blocked as the hosts looked to respond, before a cross from Glennon was caught by keeper Steve Arnold.
Clarke was the next to have a chance as he met Hendrie's cross from the right but the striker's header was also caught by Arnold.
But it was the away side who were looking the more dangerous of the two and they won another corner on the right on 16 minutes. Again, it wasn't fully dealt with but after the ball was sent back into the penalty area by Nicky Adams, Waterfall headed clear.
The first yellow card of the game was shown to Ohman for a foul inside his own half but the resulting free kick caused no problems as Adams' delivery was claimed by Russell.
A home penalty shout was waved away by the referee after Tilley worked his way into the box and went down. Northampton broke quickly and created a chance but Hoskins' shot was saved.
A stoppage came when Hanson went down with an injury and when he was ruled unfit to continue, Town were forced into the game's first substitution as Green came on in his place.
Soon afterwards, the away side doubled their advantage when the ball was played to MORTON and he steered a low shot past Russell and into the far corner of the net from the edge of the box.
Adams fired over the bar from 25 yards as Northampton continued to dominate, before a Mariners corner on the right was headed out for another one. This time, Clarke's delivery was met by Waterfall but his header was straight at Arnold.
A corner then came at the other end on 35 minutes but it was cleared at the near post.
Morton won another corner soon afterwards after a break by the visitors but the short delivery was brought clear and a through-ball found Grandin in acres of space on the left. He advanced and cut inside before curling his shot wide.
Grandin had another chance seconds later after a low cross was diverted into his path. This time, the midfielder was denied by a good save from Arnold.
Another shot by Grandin was blocked for a corner on 40 minutes but as the ball came in from Clarke, Waterfall was penalised for a foul on defender Scott Wharton as they challenged for it.
Four added minutes were played at the end of the first half and in the first of them, a shot by Tilley was deflected away for a corner, which was headed clear.
Town were finishing the half on the attack and they won another corner on the right, which led to Grandin's header dropping just wide of the far post.
That proved to be the last opportunity before the interval as Northampton went in with a two-goal lead and the Mariners had left themselves with plenty of work to do if they were to take any points from the game.
Town boss Ian Holloway used both of his remaining substitutions before the restart as Garmston and Vernam were sent on in place of Ohman and Grandin.
The away side created the first chance of the second half when Goode went through down the right and took the ball past Russell as the keeper came off his line. The defender could not take advantage though, hitting the side-netting from a narrow angle.
A run down the right by Marshall led to him crossing but the ball was just too high for Vadaine Oliver to connect with a header at the far post.
At the other end, Vernam kept the ball in on the right and crossed but Clarke's shot went just wide.
A foul by Glennon on Oliver gave the visitors a free kick midway inside the Grimsby half and Adams chipped it for Wharton at the far post, although his header back across goal was cleared by Green.
Another free kick came soon afterwards after a foul by Tilley and this time, Adams' ball went through to Russell.
Chris Lines replaced Oliver and Scott Pollock cme on for midfielder Alan McCormack as Northampton manager Keith Curle made a double substitution just before the hour.
Marshall won a corner on the right on 64 minutes and after the ball was eventually played into the box, it was half-cleared and a low shot came in from Pollock which was gathered by Russell at the second attempt.
A foul by Goode on the Town left earned him a talking-to from the referee but the resulting free kick came to nothing as Benson's ball sailed out for a goal kick.
Goode was seeing plenty of action at both ends of the pitch and his low cross had to be put behind by Hendrie for a corner. Waterfall headed the ball away when it was eventually played into the box but it dropped for Jordan Turnbull, whose volley led to another corner after Russell couldn't hold it.
A cross from Adams on the away left was cut out for a corner and after it was not fully dealt with, the ball came back in but Wharton's header was caught by the keeper.
Town had a chance to halve the deficit when a cross from the left was dropped by keeper Arnold but Clarke could not take advantage as he volleyed over the bar.
Michael Harriman replaced Marshall as the visitors made their final change with 11 minutes to go.
And two minutes later, the away side made sure of the points when they grabbed a third goal. A loose pass from Waterfall let MORTON in and he made no mistake, taking the ball forward and slotting it past Russell.
Three added minutes were played at the end of the game, with the Mariners looking for a consolation goal.
But it was not to come as Northampton saw out the remainder of the contest to ensure a clean sheet to go with their three goals.
Town will look to bounce back when they are next in action away to Plymouth Argyle on Tuesday.
- Sam Russell
- Luke Hendrie (C)
- Anthony Driscoll-Glennon
- Luke Waterfall
- Ludvig Öhman
- Josh Benson
- Harry Clifton
- Elliot Grandin
- James Hanson
- Billy Clarke
- James Tilley
- James McKeown
- Bradley Garmston
- Elliott Hewitt
- Elliott Whitehouse
- Matt Green
- Ahkeem Rose
- Charles Vernam
- Steve Arnold
- Jordan Turnbull
- Scott Wharton
- Charlie Goode (C)
- Mark Marshall
- Nicky Adams
- Alan McCormack
- Ryan Watson
- Sam Hoskins
- Callum Morton
- Vadaine Oliver
- David Cornell
- Michael Harriman
- Lloyd Jones
- Chris Lines
- Scott Pollock
- Morgan Roberts
- Harry Smith
Referee: Chris Pollard
Attendance: 4,879 (303)
Possession: Town 59%-41% Northampton
Next Up: Plymouth Argyle (A)