Folkestone's promotion dream turned into a nightmare when they were humbled at home in the play-off final by Merstham.
Having come into the game on a 15-match unbeaten run, Neil Cugley's side dominated the first half but they trailed 2-0 at the break following goals from Taurean Roberts and Tutu Henriques.
Fabia Saraiva added a third shortly after the restart and the visitors closed out the game with ease to consign Invicta to another season in Ryman League Division 1 South.
This was a second successive play-off final defeat for Cugley's men, who were beaten here on penalties by Leatherhead a year ago.
Most of the 1,465 inside the Fullicks Stadium went away dejected - and before the match had finished.
Folkestone were unchanged from Tuesday's semi-final win over Whyteleafe, which meant Ronnie Dolan had recovered from an ankle injury to take his place in midfield.
The Invicta side featured four players - Liam Friend, Frankie Chappell, Josh Vincent and Micheal Everitt - who were part of Folkestone's promotion-winning team in 2009/10.
Top scorer Ian Draycott led the line with Richard Atkins, while Jon Pilbeam and former Gills youngster Ashley Miller again had to settle for a place among the substitutes.
Merstham, also unchanged from their penalty shootout win at Faversham in the semi-finals, were captained by ex-Maidstone midfielder Saraiva.
The home side got into their stride from the first whistle, playing some neat football on the edge of the box, although Merstham opened the scoring with five minutes on the clock.
As Invicta waited for an offside flag which never came, right-back Simon Cooper steadied himself before drilling the ball across goal for Roberts to slid in and score.
Thereafter, Folkestone made most of the running in the first half.
Dolan's set-pieces looked like their best route to goal. Everitt had a header cleared off the line from one of Dolan's corners, before another was nodded over by Chappell.
Jordan Wright and Matt Newman had volleys from the edge of the box charged down as the home side kept pressing for an equaliser.
A flare-up between Chappell and Marc Okpoye on the edge of the visitors' box led to Folkestone's next chance. Okpoye, having fouled Chappell, was perhaps lucky to escape further punishment when he appeared to move his head towards the Invicta centre-half in the confrontation which followed.
Goalkeeper Brannon Daly dived low to his left to keep out Draycott's powerful free-kick and Atkins had his head in his hands when he failed to convert the rebound.
At the other end, Saraiva tried to catch out Tim Roberts when Merstham won a free-kick wide on the right but the goalkeeper was wise to Saraiva's snapshot and saved easily.
Folkestone kept hammering on the door and when Draycott cleverly turned Matt Newman's pass into his path, Atkins burst into the box and rattled a shot against the woodwork.
A neat move on the edge of the Merstham box then saw Wright beat Daly to Atkins' through-ball, only for his lob to drop agonisingly over the crossbar.
Those missed chances came back to haunt the home side when Merstham doubled their lead in stoppage-time.
Tommy Hutchings had just seen a shot blocked by Chappell when Henriques was allowed to rise unmarked and head Saraiva's left-wing corner beyond Roberts from only a few yards out.
Things got even worse for Folkestone six minutes into the second half. Merstham were awarded a free-kick 30 yards out and Saraiva swept a sublime shot into the bottom corner, with Roberts left grasping thin air.
Daly pulled off another good save when Draycott rose to head Josh Vincent's floated right-wing cross towards the far post but it could, and probably should, have been 4-0 moments later.
As the Folkestone defenders stood around and watched, Peter Adeniyi turned in the box and fired a shot just past the post.
Draycott fired a free-kick into the Merstham wall and that rather summed up the frustration around the ground as time ticked away.
More confusion in the Invicta ranks allowed Okpoye to fire a shot straight at Roberts.
Merstham were packing their defence now but they still posed a threat going forward. Hutchings, having taken over the armband from the substituted Saraiva, sent a free-kick from distance whistling past the far post with Roberts beaten.
By now, chances were drying up as quickly as Folkestone's hopes of a comeback. Atkins turned smartly on the edge of the box but he failed to hit the target.
Folkestone were a spent force and Merstham might even have added to their tally in the dying moments through Cooper and substitute Reece Hall.
They celebrated wildly when referee Gary Parsons blew for time, while the dejected Folkestone players were left with that familiar empty feeling on their home ground.
Folkestone: Roberts, Vincent, Chappell, Friend, Blanks, Dolan (Pilbeam 53mins), Everitt (Miller 74mins), Newman, Wright, Atkins, Draycott. Subs not used: Wraight, Austin, Fender.
Merstham: Daly, Cooper, Douglas, Morath-Gibbs, Okpoye, Henriques, Roberts, Adeniyi, Hutchings (Kaffo 84mins), Saraiva (Folkes 66mins), Rhule (Hall 82mins). Subs not used: Gunner, Makiese.