Grimsby Town were beaten for the first time under Ian Holloway as promotion-chasing Exeter City won at Blundell Park.
The Mariners matched their opponents for long periods of the game and were inches away from a half-time lead when Elliott Whitehouse hit the post.
They were denied by the woodwork again in the second-half following a Billy Clarke header and instead, the only goal of the game was scored by Nicky Law for the visitors.
After the goal, both sides had chances but try as they did, the Mariners were unable to find an equaliser.
The Town boss made two changes to his starting XI from the draw at Leyton Orient last time out, with Clarke making his first start for the club in place of Ahkeem Rose and Ludvig Ohman coming in for Harry Davis.
Clarke was also marking his home debut alongside Anthony Glennon, while the other two January signings, Josh Benson and James Tilley, were both named on the bench.
James McKeown started in goal, with Luke Hendrie, Mattie Pollock, Ohman and Glennon forming the defence.
Harry Clifton, Jake Hessenthaler and Whitehouse were the unchanged midfield trio, while Max Wright and Charles Vernam lined up with Clarke in attack.
Benson and Tilley were joined as substitutes by James Hanson, Elliott Hewitt, Brandon Buckley, Joe Starbuck and Sam Russell.
Exeter arrived in Cleethorpes riding high in League Two, with the Grecians sitting in second place and 20 points better off than the 17th-placed Mariners.
But Matt Taylor's men would be out for revenge after the Mariners' superb performance in the reverse fixture in Devon saw them run out 3-1 winners in September.
A shot from Vernam was blocked after a great cross-field pass by Pollock had launched Town's first attack of note on four minutes.
Exeter's reply came through Brennan Dickenson, who set off on a run into the Grimsby penalty area but overran the ball and it went through to McKeown.
The hosts were playing plenty of good football in the early stages of the game and a ball from Whitehouse found Glennon on the left but his cross was caught by visiting keeper Jonny Maxted.
A good chance for the away side came on 19 minutes when a cross from Dickenson on the left was put behind for a corner. From the flag-kick, the ball reached Pierce Sweeney at the far post but his volley went over the bar.
At the other end, a close-range shot by Wright was pushed over the bar by Maxted for a corner, which was cleared.
A shot by Exeter's Randell Williams was pushed behind for a corner by McKeown, before a foul on the away right gave them a free-kick and it led to the keeper doing well to block a Sweeney header for another corner, which was cleared.
A cross from Wright was headed behind for a Town corner on 32 minutes and after Exeter striker Ryan Bowman was yellow-carded, the flag-kick eventually led to another one on the right. This time, the ball came to Hessenthaler on the edge of the box but his shot was stopped by Maxted.
Another away corner came on 35 minutes and was comfortably cleared, then midfielder Archie Collins did well to chase back and deny Vernam with a good challenge after the ball had been played forward for the striker to chase.
A deflected shot by Lee Martin brought another corner four minutes before the break but the ball was caught by McKeown after it had been headed back across goal.
The Mariners were inches away from taking the lead a minute later when after a good build-up, Whitehouse curled a shot beyond Maxted but could only watch as the ball came back off the far post and was scrambled away for a corner before Vernam could get to the rebound.
Clarke was denied by a good save from Maxted as the striker's low effort was blocked by the keeper's feet, with the resulting corner cleared as the Mariners ended the half strongly.
One additional minute was played at the end of the half and with no further chances for either side, it remained goalless at the break.
No changes were made before the restart and Exeter won an early corner in front of their travelling supporters, which led to the ball bouncing around the penalty area until Clarke was able to win a goal kick.
Town went close to taking the lead on 50 minutes after Hendrie's cross was met by Clarke but the ball was cleared off the line after his header had been tipped onto the post by Maxted.
Tilley was sent on for his Mariners debut on 57 minutes as Wright made way and a home penalty appeal came soon afterwards when the substitute went down under a challenge as he looked to meet a low cross from Clarke. The claims were waved away by the referee.
Dean Moxey replaced Dickenson and Joel Randall came on for Lee Martin as the away side made a double substitution with 65 minutes on the clock.
And three minutes later, the visitors broke the deadlock when they capitalised on a mistake and LAW kept his composure, worked the space to shoot and fired past McKeown.
Hanson made his return from injury to the Town frontline as he was sent on in place of Whitehouse straight after the goal as the hosts looked for a reply.
The Mariners won a corner but a shot from Tilley was blocked, before a chance came for the visitors to double their advantage when Williams crossed for Bowman but he could only turn it wide of the near post.
Ohman had to concede a corner on 74 minutes as Exeter continued to look for a second goal but the ball from the flag was punched clear by McKeown.
Benson then became the latest to make his Grimsby debut as he replaced Hessenthaler with 15 minutes to go.
But the away side almost wrapped the points up a minute later when Randall got in behind the Town defence to run onto a ball from Bowman and go clean through on goal. The striker could not take advantage though, sending his shot wide as McKeown rushed off his line.
A foul on Tilley brought a free-kick midway inside the Exeter half and after the visitors failed to fully deal with it, the ball was played back into the box but Clifton could only flick a header through to keeper Maxted.
Randall went close again at the other end with a shot that curled just wide of the far post on 81 minutes, before an overhead volley by Clifton just cleared the bar as Town kept looking for an equaliser.
An opportunity for the home side came when the ball was played through for Hanson but after he was forced wide, the striker's chip towards the far post was cleared from danger.
Soon afterwards, Maxted made a brilliant save when he dived full-length to push a first-time thunderbolt from Clarke away for a corner.
Four additional minutes were played at the end of the contest but the Mariners were unable to find an equaliser and instead, the visitors took the points
Town are next in action on Saturday, when they travel to Crawley Town.
Town: McKeown (C), Hendrie, Pollock, Öhman, Glennon, Clifton, Hessenthaler, Whitehouse, Vernam, Clarke, Wright.
Subs: Russell, Tilley, Hewitt, Buckley, Starbuck, Benson, Hanson.
Exeter: Maxted, Parkes, Martin, Sweeney, Williams, Dickenson, Taylor (C), Law, Collins, Martin, Bowman.
Subs: Ward, Moxey, Ajose, Jay, Seymour.
Referee: Andy Haines
Attendance: 6,021 (180)
Possession: Town 59%-41% Exeter
Next Up: Crawley Town (A)