And in the most dramatic manner possible. The Robins turned around at half time trailing 2-0 at Culver Road - with few complaints.
Not only did Hassocks get themselves back into the tie, but they then went and won it via a 92nd minute goal from Kian Nandhra.
The late heroics were good. But the most impressive aspect of this victory was the way in which a Robins side who are not used to losing reacted to, well, losing.
Hassocks have been defeated only once in 21 games across all competitions this season. Falling behind was always going to be a test. Falling two behind? In a County Cup final? A proper test.
Neither side had created much when YM opened the scoring on 13 minutes. Lewis Shivranain escaped down the left and his low cross was tucked past Fraser Trigwell from close range by Luke Roberts.
A couple of Hassocks half chances followed. Sam Fernley charged down the right, danced past two defenders and crossed into the box.
YM goalkeeper Alex Barker did well to punch clear. The ball landed at the feet of Oscar Kemp, who hooked the rebound volley just over the bar.
The next Robins chance was fashioned from down the other flank. Evan China teed up Kemp for a shot deflected just wide. From the resulting corner, Dan Allen headed off target.
YM rattled the bar from a corner of their own on 34 minutes, Danny White rising to produce a satisfying thwack against the woodwork.
Less enjoyable was YM doubling their lead three minutes later in a role reversal from the opener. Roberts turned provider, playing Shivranain over the top of a static Robins defence to lob beyond Trigwell.
Nandhra almost pulled one back before the break when a lovely passing move worked him in. The angle though was tight and he dragged just wide.
The next goal was clearly going to be crucial. And it went the way of Hassocks 12 minutes into the second half. Nandhra rode a couple of challenges to get one-on-one with Barker. He could have gone for goal himself but selflessly squared to give Kemp a tap in, halving the deficit.
With that, the momentum began to change. Trigwell made his last contribution by gathering a difficult cross and then making an excellent save on the stretch.
YM were beginning to panic as Hassocks started to finish strongly. The introduction of two livewire Robins wingers in Ethan Brasier and Oliver Goswamy caused an incensed level of manic worry.
Gosway showed quick enough feet at one point to skip past three defenders without so much as breaking a sweat. As for Braiser, praise does not come much higher for a Hassocks winger than being described as Jack Troak junior. Brasier has the skill, posture, enthusiasm and hair of Troak.
Almost all of Troak’s first team teammates were gathered behind the goal the Robins were attacking in the second half; a sign of how connected Hassocks are as a club that the senior squad give up their Monday nights to watch the Under 23s.
They celebrated wildly when the equaliser arrived on 72 minutes. Brasier cut inside from the left to find Goswamy on the right wing. It would be lazy to reach for another first team comparison at this point, but the way Goswamy sailed effortlessly through the YM defence was Big Alex Fair like.
The decision from Goswamy to then try an outrageous scoop pass across the face of goal was also something from the Fair playbook. But it worked as Kemp headed home from close range to make it 2-2.
That left penalties looming until two minutes into injury time. Substitute Harry Hammond wiggled some room down the right and his low cross into the box was deftly carressed inside the far post by Nandhra,
With that, a first ever Under 23s County Cup was in the bag. Seven of the Hassocks squad will return to Culver Road in two weeks when the Under 18s play their County Cup final. This is turning into some season for Hassocks across all levels.
Hassocks: Trigwell, Fernley, Adlington, Hicks, Fernley, McHale, Jenkins, Nandhra, Kemp, China, Gladding.
Subs: Brasier, Goswamy, Hammond, Hendy, Charman.