With an air of inevitability, a side who finished 31 points below them in the league dumped them out of the play-offs on a night when they never looked anything like their best.
After going 2-0 down inside the first half-hour, the Rocks found hope in the form of a sublime Ben Johnson free-kick just before half-time.
Heavy pressure from the Rocks in the middle of the second half saw them hit the underside of the bar and force the Dulwich keeper into two superb saves.
After that, Hamlet scored again, the atmosphere died and the Rocks faithful were left to reflect on a season which held so much entertainment, quality and promise yet ended without promotion or the title to show for it.
Now they must go away, get over it and do it all again in the same division next season – and next time the aim must be to make sure of top spot and leave nothing to the unbalanced lottery of sudden-death against teams who don’t really deserve to be on the same pitch.
The omens were not good as early as when the teamsheets were handed out - these showed that the Rocks were without midfield duo Michael Birmingham and Kane Wills, who both suffered knee injuries at Chatham.
Perry Ryan and Dan Royce got the nod to replace them in the starting line-up.
It was supposed to be a night for Saturday’s title heartache to be forgotten against a Dulwich Hamlet side who must have looked upon their play-off place as a bonus and something from which they had nothing to lose.
The Rocks were the first to have an effort at goal, Dan Royce’s volley flying wide in the fourth minute.
Nyren Clunis drove into Craig Stoner’s side netting in the seventh minute after a mistake by Matt Whitehead inside his own half which typified a nervy start by the home side - and that was a warning shot that wasn’t fully heeded.
Luke Nightingale suddenly found some space to run at the Dulwich defence. He teed up Jason Prior but his low shot was weak and easily gathered by Stuart Robinson.
Dulwich took the lead in the tenth minute with the simplest of goals. Whitehead conceded a corner and when Ahmed Deen swung it to the far post, Lewis Goncalves was free to get up and nod it back past Stoner.
It was a worrying opening to the game for the Rocks and the task ahead of them was getting bigger all the time.
Royce set up the best Rocks’ chance to date in the 16th minute with a flying run down the right and a cross to the near post where Johnson’s volley was almost spilled by Robinson, who gathered it at the second attempt before Prior could pounce.
Stoner did well to hold a Deen free-kick curled into the danger area, under pressure from a forward.
Another raid down the right, this time from James Crane, resulted in a cross which Prior headed over when well-placed at the near post.
There were signs that the Rocks were starting to find some fluency after their slow start and that, in turn, lifted the home crowd.
But another Whitehead mistake set up Clunis for a shot which struck a hand for a free-kick just outside the Rocks boss. Deen curled the free-kick well wide.
Royce went into the book on 27 minutes for a late foul on Gary Drewett after losing possession to him as the Rocks tried to build down the right. And things got worse for the Rocks from the free-kick, which was floated in from the left touchline for Drewett – again unchallenged - to head past Stoner.
The Rocks tried to hit straight back and Johnson beat his man inside the box but sent over a cross that Robinson plucked from the air.
Royce risked a red card by kicking the ball away after having a free-kick given against him as he tried to beat his man on the right wing.
Clunis made it 1-1 on the bookings front when he was yellow-carded for leaving a foot in on Stuart Axten.
A Johnson free-kick swung in from the left looked promising but Prior misdirected his header.
Then from nowhere, in the 42nd minute, the Rocks were back in it when Johnson curled a peach of a free-kick into the top corner after Johnson himself was fouled a couple of feet outside the box. That brought the game – and the crowd – to life again after the night had threatened to turn into a flat one.
Within a minute Crane found Royce down the right and his cross beat the keeper, but was beyond Nightingale as well.
The start of the second half brought brief spells of pressure from first the Rocks then Dulwich, but it was pressure without an end product.
As in the first half, the Rocks were giving the impression they had yet to wake up – perhaps the half-time break had come at the wrong time for them.
There were 601 inside the ground, perhaps a little disappointing for such a big game given that more than twice that number had seen Worthing beaten eight days earlier.
Johnson was so close to his and the Rocks second just before the hour when he ran at the backtracking Dulwich defence and struck the underside of the bar. The ball bounced down and out – and just too high for Prior to nod in the rebound.
Royce was denied by a point-blank save by Robinson as he met a long ball to the far post with a toe-poke – then Robinson was the Hamlet hero again with a brilliant stop to tip away Tim Bond’s header from a Johnson free-kick.
Stoner was equally impressive at the other end to keep out a close-range header, not knowing the linesman had indicated offside.
Dulwich wanted a penalty as Clunis stumbled under Whitehead’s challenge as he raced through on goal but it wasn’t given. Not for the first time, the histrionics of the visitors’ bench left much to be desired.
Prior was inches away from an equaliser on 72 minutes when he ran on to a pass and walloped a shot goalwards that a defender deflected just past the post with the keeper scrambling to get there.
The Rocks brought on Matt Wood for Dan Beck with 17 minutes left.
But on 75 minutes Dulwich scored a killer third. Clunis, who had been a thorn in the Rocks’ side all night, got away down the left and crossed for Ray Powell to bundle it past Stoner from close in.
Dean Maynard was immediately tasked with a major rescue act, replacing Royce.
There was a flashpoint with 12 minutes left when a Dulwich player went down in the box with the ball out of play. It led to a melee involving more than a dozen players The end result to the ugliness was yellow cards for Johnson and Gerry Gonnella.
As time ran out on the Rocks’ dream, Whitehead got to the byline to send in a decent cross to the near post which Robinson grabbed.
Dulwich made a change, bringing on Kevin James for Powell.
Sub Wood fired a well-struck shot wide with four minutes left and hope was beginning to evaporate for the home side.
The final chance within the 90 minutes came and went when Johnson’s cross into the six-yard box was flicked away from a Rocks head.
Six minutes added on never looked like changing the course of what turned out to be a thoroughly-depressing, mentally draining night.
Dulwich celebrated as though they had won promotion and now face Leatherhead in Saturday’s final. It’s fair to say most Rocks fans will want Leatherhead to win - if only because then at least the second promotion spot would be taken by a team who have been in the top four all season.
Rocks: Stoner, Crane, Whitehead, Ryan, Axten, Bond, Royce, Beck, Prior, Nightingale, Johnson. Subs: Maynard, Marzetti, Turner, Wood, James.
Dulwich Hamlet: Robinson, Morath-Gibbs, Deen, Francis, Duku, Goncalves, Clunis, Gonnella, Powell, Pinnock, Drewett. Subs: Rose, Gradwell, Bowen, James, Kamara.
Ref: A Degnarain (Islington)