The U's earned a vitally-important maximum at the home of Crawley Town on Saturday afternoon, whilst the Mariners upset the odds and defeated Crewe Alexandra on their own patch.
Match preview
Following back-to-back home defeats versus the top-two outfits in League Two - Wrexham and Stockport County - Colchester have given their hopes of avoiding the drop into National League football a massive boost by coming out on top of a five-goal thriller versus Crawley on Saturday afternoon.
Having found the net on just one occasion so far in the fourth tier, hard-working striker Tom Hopper tripled his League Two tally for the campaign in one glorious afternoon at Broadfield Stadium by bagging a brace, with Northern Irishman Cameron McGeehan also getting onto the scoresheet for the U's.
Despite being widely known in the football world as a head coach who is used to achieving things at the upper echelons of the division after his successful period at Lincoln City, former Huddersfield Town boss Danny Cowley has a more humble aim this term in keeping Colchester in the Football League.
After earning that much-needed three points at Crawley, the U's have moved themselves out of the bottom two in the fourth-tier standings ahead of Tuesday's visit of Grimsby, with United one point ahead of 23rd-placed Sutton United despite having played two games fewer than Steve Morison's troops.
Colchester have battled on tremendously this campaign after losing their leading marksman in January, when 11-goal youngster Joe Taylor was recalled by parent club Luton Town and subsequently loaned out to Lincoln in League One, with the Hatters feeling that his development would be accelerated elsewhere.
Grimsby have all but secured their place in League Two for a third-straight season after comfortably dispatching of playoff hopefuls Crewe at Mornflake Stadium on Saturday afternoon, when the visitors managed to record their biggest victory in all competitions since December 29's battering of Salford City.
The Mariners were in control of the contest at the half-time interval courtesy of Toby Mullarkey, and the hosts were unable to contain Grimsby as they continue to breach the net of Max Stryjek, with Curtis Thompson and substitute defender Denver Hume getting onto the scoresheet during the second period.
Although Grimsby will definitely finish below last season's standing of 11th, David Artell's side come into Tuesday's clash in the knowledge that one more point from their last three matches of the 2023-24 term will secure their spot in League Two until at least the summer of 2025.
Saturday's hammering of Crewe was only the Mariners' second fourth-tier away win of the campaign, and no other side in the division have managed fewer victories on the road than Grimsby as the term draws to a close, meaning that Colchester have plenty of cause for optimism on Tuesday.
After forming a key part of Stevenage's promotion-winning campaign of 2022-23, Danny Rose swapped the Lamex for Blundell Park during the summer transfer window and has not looked back since, netting 13 goals and providing three assists in 37 League Two appearances for relegation-fighting Grimsby.
Colchester United League Two form:
D
W
D
L
L
W
Grimsby Town League Two form:
L
L
D
W
L
W
Team News
After receiving his marching orders during his cameo off the bench in the win at Crawley, Samson Tovide will be unable to feature for Colchester on Tuesday night.
The absence of the 20-year-old limits Cowley's options at the top end of the pitch, although the likes of Conor Wilkinson and John Akinde are still available to provide different skill sets from the bench.
Despite conceding twice at Crawley last time out, the U's should continue with a back three of Connor Hall, Thomas Dallison and Jay Mingi on Tuesday night.
Grimsby are likely to be without the services of top goalscorer Rose, who was forced off just 22 minutes into the beating of Crewe on the weekend.
Justin Obikwu will require a new partner at the focal point of the Mariners' attack should 30-year-old Rose be unfit, with Donovan Wilson the most-obvious candidate for that particular role.
Although he found the net off the bench, left-back Hume is set to be kept out of the XI once again by Charles Vernam as Artell looks to field an unchanged side.
Colchester United possible starting lineup:
Hornby; Mingi, Dallison, Hall; Fevrier, Smith, Read, Chilvers, Iandolo; Hopper, McGeehan
Grimsby Town possible starting lineup:
Eastwood; Mullarkey, Tharme, Rodgers; Smith, Thompson, Green, Vernam, Holohan; Wilson, Obikwu
We say: Colchester United 1-1 Grimsby Town
Colchester will be full of confidence following Saturday's win at Crawley, however we cannot envisage the U's winning back-to-back matches in League Two.