Holohan’s 89th winner sparked wild celebrations inside The Vic as Pools started the League Two campaign with a big win.
It was late but deserved win for well-drilled Pools, who carved out the better chances against a poor Crawley Town side.
It has been a difficult summer given how tight the turnaround was between winning promotion in the play-off final in mid June and the start of the new League Two campaign.
Challinor has worked hard to add to bolster his squad to this point but further signings are needed with Pools clearly still lacking at least another striker.
Had Luke Armstrong and Rhys Oates still been at the club then this game and win would have been a lot more convincing.
However, that is the reality facing Pools, those two have moved on to pastures new and Pools need to add at least one more striker to replace their goals in the squad.
For now though, Pools and Challinor can reflect on a job very well done.
Dave Challinor handed starts to new signings Neill Bryne and Olufela Olomola, the rest of the starting XI made up of players who had played their part last season as Pools won promotion.
The ‘wolfpack’ remained the midfield trio, captain Nicky Featherstone with Mark Shelton and Gavan Holohan either side of him.
There were large queues outside The Vic as kick-off approached, with a few dozen fans still waiting to get in 10 minutes after the game had started, such was the interest in the return to the Football League.
Pools, lining up in their usual 5-3-2- formation, with Luke Molyneux partnering new stiker Olufela Olomola up front.
Gary Liddle at the heart of the Pools defence, with Timi Odusina to his left and new signing Neill Bryne to his right.
It was a solid start to proceedings by Pools, a fairly uneventful opening 15 minutes saw few chances, the only one of note saw David Ferguson cut in from a corner on the right only to see his effort curl just wide of the post.
The North West Corner giving the players their full backing from the off, with The Vic packed with supporters after much of last season was behind-closed-doors.
Jamie Sterry looked the part at right wing-back, with two excellent crosses in the opening stages.
Pools were on top in the opening 25 minutes and they should have been ahead when Gavan Holohan fired an effort wide, Bryne couldn’t convert it at the back post.
It was a big chance missed by the hosts. Shortly after Luke Molyneux saw his deflected effort easily gathered by Glen Morris.
As the game edged towards the half hour mark one or two passes began to go astray from the hosts. The Crawley support, backed by a drummer in the Rink End, attempted to rally their side.
Crawley enjoyed a spell of pressure as the game edged towards the break, a run of corners and free-kicks but the delivery was poorly executed and Pools were able to clear comfortably enough.
With 40 minutes on the clock, Sterry again produced an excellent cross from the right flank, dinked to the back post but the onrushing Ferguson could only nod down into the turf and over the bar.
Goalless at the break, the second half started in a similar fashion to the way the first ended.
With 55 minutes on the clock, Olomola forced Morris into a save with a low effort.
It wasn’t going to break the deadlock but an effort on target at least.
It was a solid enough debut from Olomola, he started the game well but his influence waned as it wore on.
Five minutes later and his debut was over, Challinor bringing fellow new signing Tyler Burey on for Olomola to freshen things up.
The 20-year-old was Pools’ seventh summer arrival earlier in the week after Neill Byrne, Reagan Ogle, Martin Smith, Fela Olomola, Jake Lawlor and Mark Cullen. Fittingly, he was wearing the number 7 shirt.
The game had gone flat on the hour mark, with neither side looking much like producing a moment of magic.
Burey, a winger, brought some spark to proceedings and looked to get at the Crawley defence, a willing runner, he was always looking for the ball.
There were few openings in the second half, both sides cancelling each other out.
Challinor made a final roll of the dice in the last five minutes with a double sub, Mark Cullen and Matty Daly on for Shelton and Molyneux.
And with 89 minutes on the clock, Pools got the breakthrough.
Thanks to Gavan Holohan - who else? Sterry played the ball into Burey who crossed to Holohan, took a touch before a low finish past Morris.
Cue wild celebrations in the corner of the Mill House.
A smart low finish to fire Pools ahead, the midfielder celebrating on his knees in front of the North West Corner.
‘We’ve got an Irish midfielder…’ ringing out around the ground.
It was a deserved victory for Pools, Crawley Town offered little and didn’t threaten Killip much in the Pools goal.
Chances, in truth, were few and far between but Pools had the better of them and they looked well organised again and deserved the win.
Pools are back in the Football League and back with a bang.
Pools: Killip, Sterry, Ferguson, Liddle, Odusina, Bryne, Shelton (Daly, 86), Featherstone (C), Holohan, Molyneux (Cullen, 86), Olomola (Burey, 60).
Pools subs not used: Mitchell, Lawlor, Ogle.
Goals: Holohan (89)
Crawley: Morris, Davies, Gallacher (Ferry, 60), Craig (C), Powell, Nadesan, Frost, Tunnicliffe (Dallison, 32), Matthews (Tilley, 74), Payne, Hessenthaler.
Crawley subs: Francillette, Ashford, Khaleel, Nria Noukey.
Referee: Scott Oldham