Colchester Utd 4 Carlisle Utd 1: "New players" was advanced by Keith Curle as the most obvious route back to winning form after this punishing defeat. And it is plain that some outside help would benefit Carlisle United in these tricky first days of 2017.

But it can't be the only solution. It should not be beyond the Blues boss and his coaches to get better defensive performances out of the players who are currently leaking goals and, in the process, preventing United from charging to the front of the promotion race.

"Part of my job now is not field-based, it's office-based," Curle said, suggesting that hitting the phone and moving bodies out, in order to bring "better ones" in, was top of his agenda.

Certainly, no club with high aspirations can neglect the market. But Carlisle should not be a four-goals-against team whether or not the door opens to new signings this month.

Accounting for the absence of influential defensive players, United's attempts to protect their own net at Colchester cried out for a firm hand. That means tracksuit time for Curle as well as window trading.

Carlisle's manager did not like being asked whether his team's present situation was a "potentially defining moment" in his Blues career. Curle's response to BBC Radio Cumbria 's James Phillips was to accuse the commentator of posing a "negative" question.

He also referred listeners to the league table, which shows three defeats from 25 games. Highlighting the broader picture is fair enough, and not unreasonable.

But it is still apparent what Curle needs to address with a fair degree of urgency, and one wonders whether part of the answer was staring United in the face on Saturday, wearing blue and white stripes. Colchester were going nowhere in League Two as winter approached, but a formation change by John McGreal has put them in remarkably better form.

It is true that Carlisle should have scored more than the one they got through Shaun Brisley here - Jason Kennedy was denied by an incorrect offside flag while other decent chances were missed - but nor was the result an injustice, and in Colchester's 3-4-1-2 formation, implemented at the start of their revival, it was easy to see a team in tune with its shape and strengths.

Seven wins from eight is no accident and they have not come through McGreal flashing the club's credit card. Brisley, Mark Ellis and the others who tried to keep Colchester out are experienced customers at this level who could surely be reorganised into a tighter unit.

Until now Carlisle's clean sheet aversion has not cost them greatly. And it would be melodramatic to say a crisis is at their door given they remain four points above the play-off places. But the goals-against total has not been good enough for some weeks and United should be able to sort it even without influential heads like Danny Grainger, Mike Jones and Michael Raynes, the latter missing here through illness.

Either way, a front-foot team had to be dealt with on Saturday and it was bracing to see how much joy Colchester had at times. Brennan Dickenson's pace down the left found helpful space while in midfield Craig Slater mastered possession and invention.

Those two combined early as Ellis, on his first league start since October, dealt with the first danger. No such luck in the 11th minute, as Colchester recycled a chance and Dickenson crossed for Chris Porter to bury a commanding header.

Curle stared at the floor, dismayed. United then had to withstand more confident home attacking, Mark Gillespie saving from Slater, before gaining some rhythm of their own.

When they did that, their threat was genuine. Kennedy fired a Nicky Adams free-kick over the bar, Jabo Ibehre had a header saved by Sam Walker, Kennedy failed by millimetres to reach a Charlie Wyke cross and Jamie Devitt, in central attacking midfield, started to impose his ball-playing skill and vision on the contest.

Then came the equaliser - a back-post Macaulay Gillesphey cross and a looping header from Brisley that beat the stranded Walker. It capped a good response but was not allowed to develop further for, five minutes later, Carlisle failed to shut off space around their box as Kurtis Guthrie wriggled around Devitt and found the far corner of the net.

Such is their nature, United again replied hungrily. Adams dropped a header wide and when Brisley had a volley saved and Adams fizzed it back across the box, Kennedy tapped in from close range. Replays confirmed the offside flag had been raised in haste, but Carlisle's end to the half still made you feel there was further drama in store.

Alas, too much of it was at Carlisle's end. Four minutes into the second half and their back line went all Swiss cheese again, as Richard Brindley kept the ball in play on the right, Slater found room against Gillesphey, Porter dummied his low cross and Guthrie arrived, untracked, to hammer it home.

A side in prime form did not need this much help and by contrast, Carlisle found it harder to break down the home rearguard of Tom Eastman, Frankie Kent and George Elokobi. Wyke nearly sneaked a goal from the right, and a few corners and crosses then followed, one of which saw Kennedy volley over the bar from tempting range, but this was not part of an unstoppable surge back into the game.

From Colchester there was just as much and, eventually, more. Porter should have converted a cross from the impressive Brindley while Guthrie seemed to spend the rest of the game finding different ways to avoid scoring a hat-trick.

On 71 minutes he smashed Brindley's cross against the bar. Moments later Ellis narrowly stopped him feeding Porter. Carlisle had made substitutions by now (including Alex McQueen on the right) but their strikers struggled for openings, while the normally dynamic Adams looked exasperated at times as team-mates failed to feed him.

It was finished well before the end, in truth, and the only remaining question concerned Guthrie and the destiny of the match ball. In normal time Gillespie had to gallop out of his box to tackle the striker, while in the 93rd minute a goalline Brisley block denied him as he tried to walk it in.

Eventually, though, his third came - and in a rather slapstick manner, as the backpedalling Brisley collided with Gillespie, taking a knock to the face, and after the keeper valiantly saved Denny Johnstone's shot, Guthrie slotted home the breaking ball.

There was too much disorder about the goal, frankly. Brisley came off before the end, in pain, while the rest left the field with hollow expressions a minute later.

It is not a feeling these players have been known very often this season. And maybe it is because Carlisle have been so good since August that days like this feel so bad. Yet nobody would deny there are certain problems they need to get out of their system.

Curle himself described the recent pattern of conceding as "diabolical". It should not be beyond him to correct it, with or without new faces.