Grimsby Town were beaten at home for the first time this season as Crewe Alexandra took all three points away from Blundell Park.
James Hanson had the chance to put the Mariners ahead from the penalty spot in the first half but his kick was saved by visiting keeper Dave Richards.
Crewe took full advantage and went ahead within a minute of the start of the second half as Tom Lowery opened the scoring.
Town pushed forward in search of an equaliser and had some spells of pressure but in the end, they were caught on the break as Charlie Kirk made it 2-0 in added time.
Grimsby boss Michael Jolley named the same starting XI as he did last Saturday for the 3-1 win at Walsall.
That meant there was no place from the start for Sunderland loanee Ethan Robson, who did begin the midweek Leasing.com Trophy defeat by Scunthorpe United after securing a deadline day move.
James McKeown started in goal, protected by a defence of Elliott Hewitt, Ludvig Ohman, Luke Waterfall and Luke Hendrie.
Jordan Cook, Jake Hessenthaler and Elliott Whitehouse were the midfielders, with Matt Green, Hanson and Moses Ogbu forming the attack.
Robson was named on the bench alongside Liam Gibson, Charles Vernam, Harry Cardwell, Sam Russell, Mattie Pollock and Max Wright.
Crewe came into the game sitting third in League Two, a point and a place ahead of the Mariners in the early table.
They would look to attackers Daniel Powell, Chris Porter and Kirk to cause problems for the home defence, while former Town loanee Olly Lancashire was among those looking to keep the goals out at the other end.
Crewe started the game on the attack and after keeping possession well, Daniel Powell cut into the Town penalty area but was stopped by a good challenge from Ohman.
The visitors were looking to play a patient, possession-based game and they dominated the early stages of the contest, albeit without testing McKeown, as Town employed a more direct approach.
A foul on Ogbu on halway gave the home side a chance to launch an attack of their own on 10 minutes but Hessenthaler's delivery to the edge of the box was headed back to Richards.
A good ball into the box from Hendrie on 14 minutes was heeaded on by Hanson but Green's effort was blocked for a corner. Hessenthaler's cross from the flag-kick was met by Hanson but the ball went through to Richards.
At the other end, a cross from Perry Ng on the right beat everybody and went out for a goal kick, before midfielder Ryan Wintle shot over the bar from 25 yards after a tricky run through the middle by Lowery.
Town won a corner on the right after a Hewitt throw-in was headed out. Hessenthaler played it short to Hewitt but nobody could profit from his cross.
Crewe were the next to threaten after a cross from Lowery but Kirk headed just wide.
The Mariners were then given a golden opportunity to open the scoring when Hendrie was pushed over inside the box by Powell and the referee pointed to the penalty spot. Hanson stepped up but could not beat Richards, who made a good save. Town got the ball back into the danger zone but it was put out for a corner, which was cleared.
A header from Paul Green was flicked wide after a cross from Powell on the Crewe right, before Town won a corner at the other end after Ogbu had linked up with Whitehouse but the whistle blew for a free kick to the away side as Hessenthaler's flag-kick came across.
Ogbu was fouled by Lancashire to give Grimsby a free kick inside the Crewe half on 38 minutes but Hessenthaler's delivery was too strong and went out for a goal kick.
A cross from Ng was deflected behind for a corner in the last minute of the half but Harry Pickering's ball beat everybody and went out for a goal kick.
One additional minute was signalled to be played an with no further opportunities for either side, the game remained goalless at the break.
No changes were made before the restart and within a minute, the deadlock had been broken as the visitors took the lead. LOWERY got the ball on the edge of the Town box and advanced before finding the space to fire past McKeown and into the far corner of the net.
Crewe threatened again from a free kick given for a foul by Hanson but the ball from it was eventually cleard for a throw-in.
The away side's strong start to the second half continued as a low cross from Ng was blocked for a corner.
Another corner on the opposite left flank was eventually headed down to McKeown, before a good move down the Town right led to Cook seending a low cross to the near post but it was just too far ahead of Green for him to connect with.
A cross from the Grimsby left was touched away by Richards and Ogbu's effort was blocked for a corner after Green had retrieved the ball.
Town were now pushing for an equaliser and Whitehouse was blocked for a corner on 55 minutes, which was hooked clear by Kirk.
The visitors were still creating good chances of their own though and an excellent through-ball from Green found Powell inside the penalty area but his low shot was well blocked by McKeown.
A shot by Pickering was blocked for a corner on the Crewe left on 64 minutes and Lowry's delivery from it was headed away by Hanson but the ball was worked back to Lowery, whose shot was blocked by McKeown.
The visitors almost doubled their advantage on 68 minutes when a ball from Lancashire saw Powell get in beind the Town defence. His low shot spun off McKeown towards the net but Waterfall was in the right place and managed to brilliantly clear off the line.
Wright replaced Whitehouse in the Mariners' first change of the afternoon soon afterwards, before Robson was sent on in place of Cook.
Green saw a shot deflected over the bar for a corner after a cross had been headed down by Waterfall at the far post but Town were unable to make the ball from the flag count.
Chuma Anene replaced Porter for Crewe with nine minutes to go as the visitors looked forr a second goal which would kill off the game as a contest.
Ogbu did well to work an opening for a shot from 25 yards on 84 minutes but it lacked power and Richards made a comfortable stop.
The visitors had another good opportunity to seal the points after McKeown, who had come well out of his area, lost out to Anene. The substitute ran through but Hewitt had got himself into a good position on the edge of the box and managed to block the shot.
Vernam was sent on in place of Hendrie for the last two minutes plus four added minutes as the hosts looked to rescue something from the game.
But when the game's second goal finally came, it was Crewe who sealed their victory. A Town attack broke down, the visitors broke quickly and when the ball was played to KIRK, he kept his composure to round McKeown and pick his spot to beat two defendeers on the line.
That put an end to Grimsby's hopes of keeping their unbeaten home record going as an impressive Crewe side closed out what had been a deserved win.
Town are next in action on Tuesday, when Macclesfield Town visit Blundell Park for the rearranged Carabao Cup second round tie.
- James McKeown (C)
- Elliott Hewitt
- Luke Hendrie
- Luke Waterfall
- Ludvig Öhman
- Jake Hessenthaler
- Jordan Cook
- Elliott Whitehouse
- James Hanson
- Matt Green
- Moses Ogbu
- Sam Russell
- Liam Gibson
- Matthew Pollock
- Ethan Robson
- Max Wright 69'
- Harry Cardwell
- Charles Vernam
- Dave Richards
- Perry Ng (C)
- Harry Pickering
- Oliver Lancashire
- Eddie Nolan
- Ryan Wintle
- Paul Green
- Tommy Lowery
- Chris Porter
- Daniel Powell
- Charlie Kirk
- Sam Booth
- Rio Adebisi
- Nicky Hunt
- Callum Ainley
- Owen Dale
- James Jones
- Chuma Anene
Attendance: 4679 (145)
Referee: Antony Coggins
Next Up: Macclesfield Town (H)