Fleetwood are still very much a work in progress, their system and style very different from the trusted diamond which served them well through promotion and beyond.
In Amari’i Bell and Conor McLaughlin Graham Alexander has two defenders happy and willing to press forward - Fleetwood’s line up lending itself to the deployment of wing backs.
Bell, however, is yet to prove he has more than just raw pace at his disposal and he should have opened the scoring with a quarter of an hour gone.
Antoni Sarcevic was fed down the right channel by McLaughlin, pace taking him past his man.
Bell should have been there to profit, arriving at the back post but not in time to sweep home the perfectly placed cross
Sarcevic was involved in everything that was good about Town in the opening exchanges, his partnership with Jimmy Ryan starting to pay dividends - one that will likely be crucial to Fleetwood’s fortunes in the nine months to come.
Talking of Ryan, he is undoubtedly the most crucial of Fleetwood’s summer captures.
His experience and quality is telling - an oasis of calmn in a Town side struggling for composure elsewhere.
The apparent inability to quickly diffuse pressure is one of the more worrying traits Alexander’s side have developed
It cost them an equaliser on Saturday when lines weren’t properly cleared against Southend.
And it could have put them behind in this cup tie too, the defence bending under pressure, Hartlepool allowed too much time inside the box.
Michael Woods nearly took advantage, his blast straight into the body of Stephen Jordan.
With Fleetwood scrambling Nicky Featherstone nearly picked up the pieces, Chris Maxwell standing tall to deny the Pools midfielder an opener.
The keeper was proving a big man for Fleetwood - his movement denying Pools what looked like a certain opener.
Billy Paynter’s vision sent Rakish Bingham clear, Maxwell closing the angle enough - the striker doing the rest, too casual with his finish as he side footed the wrong side of the upright.
It was a let off for Fleetwood who were struggling to keep possession against an organised League Two side.
Miracle man Ronnie Moore was not in attendance, dealing with a family emergency, but evidence of his involvement was clear in the visitors, well drilled and not lacking in confidence.
Fleetwood’s early verve around the box had deserted them, the right-side outlet shut down - too much hit and hope, too little cohesion in Alexander’s new look side.
There were flashes of genius, a lightning break which oh so nearly yielded an opener - route one stuff down the middle, Ryan the intended target, only just beaten by keeper Adam Bartlett who was forced to head clear.
Given the slightly disjointed display half time was something of a relief - Town maybe lucky to make it to the break on level terms.
They started the second half in a higher gear, probing Pools, looking to make more use of McManus and his movement inside the final third.
But the lack of a final ball, or to be more precise somebody on the end of it was still an issue - clever football nothing without a little bit of bite.
And Pools very nearly showed the hosts how it should be done, Fenwick again the danger man, too easily skipping past Jonsson before firing a shot which Maxwell could only tip over the bar.
On their next attack the visitors proved their potency.
Danny Andrew conceded a soft free kick as he obstructed a Hartlepool runner.
Bingham’s devilish ball to the back post was met by the head of Paynter, the space gifted making the finish an easy one - Town’s Capital One Cup campaign on the rocks.
Town fell apart - Bingham almost creating a second with another pinpoint ball.
Scott Fenwick was the man on the end, Maxwell racing to meet him, taking the sting off the shot before pouncing to deny the midfielder.
A double substitution did steady the ship, David Ball making a welcome Highbury return, Bobby Grant adding bussle in the middle of the park.
But Pools had something to cling on to, defending in numbers, making it hard to Fleetwood to make increased possession count.
But Ball should have restored parity as Bell finally summoned up the courage to run at his man, the deep cross headed down by McLaughlin, Ball’s effort somehow pushed off the line
Bartlett wasn’t done there as chaos took hold in the box - Ball stabbing at goal, Highbury jumping to celebrate only to realise the net hadn’t bulged, Bartlett clinging on.
It should have given Town the sense they could haul themselves back.
But the spark gradually died in the hosts, a sense of inevitability creeping around Highbury.
It wasn’t a healthy atmosphere in which to perform, criticism increasingly audible, confidence dropping out of Fleetwood’s young guns.
And then the tap was turned on again - a last ditch flurry, so last ditch Chris Maxwell joined the party, set sprinting as Pools managed to clear their lines.
Another attack, another free kick Bobby Grant rattling the woodwork, Fleetwood so close to taking the tie into extra time but just unable to convert.
The defeat asks big questions of Graham Alexander’s young squad.
They’ll need to bounce back quickly to silence the doubt that is creeping in.