A quick two-goal salvo lead by Paul Mullin spoiled Paul Hurst's first game back as Grimsby Town manager as Cambridge United won their first away game since October.
Grimsby replied in the second half through Elliot Hewitt, however, ultimately they gave themselves too much to do late on.
Stevenage's win over Scunthorpe United ensured that The Mariners slipped into the relegation zone for the first time this season.
Story of the game
It was a nightmare start for Hurst on his return as Adam May’s deflected strike wrong-footed Sam Russell in goal and gave Cambridge the lead with less than five minutes on the clock.
Five defeats in their last seven had the visitors sliding down the table having occupied top spot earlier in the season, so they would have appreciated the slice of luck which gave them an early lead to build on.
They almost did build on that lead too as Paul Mullin played a fantastic ball over the top of the Grimsby defence to Harvey Knibbs who was denied brilliantly by Russell from close range to stop it going from bad to worse for The Mariners.
Grimsby kept the ball well in the first period, however, as they have done all season, lacked the cutting edge to create any clear-cut chances, with a pot shot from outside the box from Kyle Bennett the best they could create in the first third of the game.
Cambridge thrived on the counterattack and reaped the rewards of the spaces in the Grimsby backline as Mullin latched onto another long ball over the top and finished excellently into the top left corner to double The U’s lead.
Hurst would have been aware of the problems when taking over the team which were exasperated in the first half, with Grimsby threatening, but ultimately failing to create, and being painfully error-prone at the back.
Montel Gibson came on at half-time for Grimsby and showed his eagerness to make an impact as he smashed into Dimitar Mitov trying to head a Hendrie cross which left the Cambridge ‘keeper reeling in pain.
An inspired individual move and cross from the experienced midfielder Felipe Morais right on the byline handed Bennett a golden opportunity to pull a goal back for Town. Still, his free header skewed wide of the left post.
Cambridge weathered the storm from the hosts to open the second half, and Mullin should have wrapped up the game just after the hour mark as a Mattie Pollock slip offered him the space to fire from the centre of the box his shot flew over the bar.
Soon after Gibson had another header, this time unchallenged although saved brilliantly by the Cambridge goalkeeper as Green clipped the ball over to his strike partner as it was cleared to him from a corner.
The hosts had threatened the United goal a lot more in the second period. Finally, they got the goal they probably deserved as Hewitt’s looping header from a Bennett cross evaded Mitov and nestled into the back of the net to give Grimsby a lifeline.
The Mariners really pushed for a late equaliser, and Gibson probably thought he had got it when he flicked George Williams’ corner goalwards at the near post which Mitov saved well on the line as he crashed into his right post.
Mixed emotions for Town
At the end of a long, dark tunnel, Grimsby fans can finally see a gleaming light this week with fantastic news regarding the leadership of the club on and off the field, with a respected consortium led by wealthy Town fan Tom Shutes set to take over the club and manager Hurst returning to Blundell Park.
Hurst and Chris Doig led Grimsby into the EFL in 2016 after various near misses in the National League Play-Offs, and now after four years away they have returned.
However, they have inhabited a squad low on quality and confidence, and it was more of the same against Cambridge who were ruthless as Town fell to their third defeat on four games.
Cambridge direct and dangerous
Mark Bonner was desperate for a reaction from his side after the recent downturn in form, and against a struggling Grimsby, they went back to basics.
They were direct in their offensive approach, with both of the first-half goals from aerial balls over the defence.
They had just three shots in the first half and scored two from them, which shows that the away side's clinical edge was the difference in the game.
Cambridge United - Paul Mullin
Setting up the first goal and scoring the second excellently, Mullin was key to his side's match-winning efforts in the first half and continued his own excellent start to the season.
His 15th league goal was a cultured finish from an experienced forward and the crucial one in the game.
Grimsby Town - Montel Gibson
The young forward's introduction into the game at half-time switched the game's momentum into Grimsby's favour even if it was not quite enough to change the result.
His work rate and movement was an improvement on his counterpart Green who struggled once again in an isolated forward role.