Despite missing nine first-team players, the East Yorkshire club that finished sixth conspired to stun their big-spending hosts in one of the biggest shocks in play-off history.
Yet again Warrington’s hopes of a first league title since 1955 were utterly dashed, a feeling Robins coach Tony Smith knows only too well; he guided the Cheshire club to three Grand Finals and lost them all.
Here, though, he rightly celebrated as his underdogs produced a brilliant performance full of spirit, tenacity, sheer cussedness and - when it mattered most - no little skill to remarkably leave themselves just 80 minutes from a maiden Grand Final.
Let’s not forget, Rovers - who visit leaders Catalans Dragons on Thursday - have finished 11th in each of the last two seasons but once more they have shown they are a club on the up.
Yes, Warrington - whose coach Steve Price now heads homes to Australia - had the England midfield triumvirate of George Williams, Gareth Widdop and Daryl Clark to call upon.
However, in the end, it was the comparative rookies Jez Litten and Mikey Lewis who, along with Man of Steel nominee Jordan Abdull, who guided KR home with all the composure and subtlety their illustrious hosts lacked.
And all three hail from Hull.
A 16th minute try from Abdull gave Rovers a 6-0 interval lead and then Lewis, the diminutive 20-year-old scrum-half, scored a wonderful solo try, racing out of dummy-half and chipping ahead to regather ahead of another England star - the hapless Stefan Ratchford - in the 47th minute.
Thereafter, error-ridden Warrington continued to implode as they so often do and Rovers, led brilliantly by Shaun Kenny-Dowall, simply grew in confidence.
The victory, though, as the scoreline suggests, was built on the steeliness of their defence.
Warrington had all the early pressure but Smith’s side held firm and then scored with their first genuine attack.
Abdull dummied over on the last tackle, the hosts crumbling at the first sign of being tested.
The stand-off will have afforded himself a rueful smile; the score came after - bizarrely given how little ball his side had had - he failed with an ill-advised 40/20 attempt from a 2om restart.
Fortunately for Abdull, referee Liam Moore made him re-take it as some of his team-mates were not onside; he did not try the same kick again.
Abdull did curl over the conversion but his side were soon defending again when Matty Storton failed to claim Litten’s offload.
This time it was Ben Crooks who scrambled brilliantly to deny Toby King but his side were soon under the pump again when prop Albert Vete was penalised for a high tackle on Josh Thewlis and then again for dissent. Abdull forced an error out of Jack Hughes - Warrington’s ball control was woeful - but Jake Mamo nudged through next, falling to his knees in the process.
He tried to squeeze out a pass off the ground so but, in doing so, fumbled as Kenny-Dowall came in with another timely challenge.
Vete, the big former Melbourne Storm prop who had an eventful first stint off the bench, was sin-binned for a late hit on Widdop in the 31st minute. He barely hit him, let alone be late. It was one of those yellow cards that left you wondering just where the game is heading.
Nevertheless, Wolves continued to splutter - this is the third year in a row they have crashed out here at the first stage of the play-offs - and, when they did finally and brilliantly keep the ball alive, prop Muizz Mustapha hauled down Williams to deny another certain try just before the interval. Lewis’ brilliance got KR up and running in the second period before Abdull slotted a penalty and a drop goal either side of a Jimmy Keinhorst try.
Catalans will be wary of this side next week but, one thing is certain, there will be a new Grand Finalist on October 9.
Warrington Wolves: Ratchford; Thewlis, Mamo, King, Lineham; Widdop, Williams; Hill, D Clark, Akauola, Currie, Hughes, Philbin. Substitutes: J Clark, Longstaff, Mulhern, Ashton.
Hull KR: Dagger; Crooks, Takairangi, Kenny-Dowall, Keinhorst; Abdull, Lewis; King, Litten, Maher, Johnson, Linnett, Storton. Substitutes: Mustapha, Tate, Milnes, Vete.
Referee: Liam Moore (Wigan)