JACK Crowley's 78th minute drop goal was the difference as Munster won an Aviva Stadium classic and put themselves in the URC final in Cape Town in a fortnight's time.
Graham Rowntree's Reds upset the applecart big time as they beat their rivals Leinster for only the second time in the last 12 attempts - and for the first time since a Rainbow Cup fixture in the 2020/2021 season.
And, after 12 defeats in 13 previous Lansdowne Road visits against Leinster, this was a celebratory occasion on what had been an unhappy hunting ground and it means they will face Connacht's conquerors - the defending champions, the Stormers - on May 27.
READ MORE: Stormers 43-25 Connacht recap and result as Stormers set up Aviva clash
With the Champions Cup final against La Rochelle to come at the Aviva next Saturday, this defeat was not in the script for Leinster - and for Leo Cullen, who had gambled on resting almost all of his frontliners for next week.
That gamble didn't come off and, having lost at the semi-final stage to the Bulls last year, Leinster have one more game to salvage a season that has once more promised so much.
Crowley, who started at centre but took on the no 10 role after Ben Healy was forced off with a blood injury in the 32nd minute, turned after splitting the posts and wagged his finger a la Ronan O'Gara in his pomp for the province.
O'Gara will watch that one back with a wry smile as he begins the countdown to La Rochelle's bid to defend their title. For Munster, it is quite the end to a season that had begun so slowly as Graham Rowntree and his new coaching team took the reins.
Before Crowley's intervention, it appeared that Munster - who themselves were down big names with Conor Murray and RG Snyman among those ruled out - had blown their chance, having dominated for much of the first half.
It was Leinster who finished the opening period on top, taking a 10-6 lead into the break courtesy of former Munster lock Jason Jenkins' 38th minute try.
In fact over the course of the game the Reds lost possession on three occasions as the try line beckoned in front of the 26,795 attendance.
Will Connors was a first minute casualty after enduring the double whammy of a high tackle before hitting the ground head first, and the unfortunate back row who has had no luck with injuries was replaced by Josh van der Flier - who is just back from an ankle injury.
The resultant penalty was converted by Harry Byrne for an early lead for Leinster.
Cullen will not have wanted the world player of the year on so soon with the Champions Cup decider a week away, but van der Flier was immediately impactful as he won a turnover penalty against Munster's own turnover king Tadhg Beirne.
He was at it again in the seventh minute, ripping possession at the crucial moment as Munster threatened the try line, but Ben Healy restored parity in the 10th minute when Jack Conan was pinged for not releasing in the tackle.
Alert Munster defence saw Jimmy O'Brien into touch after Dave Kearney threatened to break through the cover, and then Leinster thought they had delivered the first real blow in an already absorbing contest when Ryan Baird stormed his way over the Reds' try line in the 20th minute.
However replays showed that Tommy O'Brien had touched the ball forward as O'Mahony beat him in the air, and the try was ruled out.
At the other end, Healy kicked Munster ahead when Rónan Kelleher was penalised but further Munster pressure failed to produce a try as Leinster's pack somehow won possession as the lineout mail marched towards the line.
Healy was forced out of the action with a blood injury but, once again, another Munster penalty to the corner came to nothing as Kelleher ripped possession from Beirne.
And Leinster added insult to injury by scoring the game's first try when Jenkins charged onto Robbie Henshaw's pass and out-paced Beirne and Craig Casey to score, with Byrne adding the extras for the half-time lead.
But it was Munster who went on the rampage from the restart. First O'Mahony, then Gavin Coombes made incisive breaks early on only for the attacks to quickly fizzle out.
Encouraged, they kept probing and got their reward in the 46th minute when Beirne was helped over Leinster's line by half the Munster pack and Crowley's conversion made it 13-10 in his side's favour.
They had the chance to double their advantage 10 minutes later in Leinster's 22 but chose to go to the corner - and again coughed up possession at the vital moment, this time Max Deegan stealing from replacement prop Josh Wycherley.
O'Mahony, who had come off with an elbow injury after only four minutes in Edinburgh the week before, was withdrawn soon after and so if Munster were going to win they were going to have to do so without their skipper.
Leinster went on the offensive and they found a way through.
Munster just about survived when Byrne's clever kick over the top sent Tommy O'Brien and Reds full-back Mike Haley in a race to touch down over Munster's line - the ball was there for O'Brien, but only for a fleeting moment and he couldn't ground it.
But respite was short-lived for the Reds and, four minutes after coming on, lock Joe McCarthy burrowed over despite the mass of red shirts on the try line to score.
Ciarán Frawley stepped up to take the conversion instead of Byrne but missed. Leinster were back in front 15-13 with 17 minutes remaining.
But that miss proved crucial.
Leinster looked in control of the situation as they had possession in Munster's 22 with five minutes remaining but lost possession when Cian Healy got ripped.
And Munster meticulously made their way downfield, biding their time before Crowley was presented with the golden chance to win it by Casey.
From just outside Leinster's 22, he struck through the ball and turned in jubilation. One more to go for the Reds now.
LEINSTER: Jimmy O’Brien (Ciarán Frawley ht), Tommy O’Brien, Robbie Henshaw, Charlie Ngatai (Liam Turner 79), Dave Kearney, Harry Byrne, Luke McGrath (Nick McCarthy 68), Michael Milne (Cian Healy 48), Rónan Kelleher (John McKee 65), Michael Ala’alatoa (Thomas Clarkson 71), Ryan Baird, Jason Jenkins (Joe McCarthy 59), Max Deegan, Will Connors (Josh van der Flier 2), Jack Conan.
MUNSTER: Mike Haley, Keith Earls, Antoine Frisch, Jack Crowley, Shane Daly, Ben Healy (Rory Scannell 32), Craig Casey, Jeremy Loughman (Josh Wycherley), Diarmuid Barron (Niall Scannell 52), Stephen Archer (Roman Salanoa 51), Jean Kleyn (Fineen Wycherley 46), Tadhg Beirne (Alex Kendellen 71), Peter O’Mahony (Jack O'Donoghue 51), John Hodnett, Gavin Coombes.
READ NEXT:
- Seamus Coleman injury latest as Sean Dyche drops hints over Everton star's future.
Paul Flynn responds to Donal Og Cusack's Tailteann Cup comments
John O'Shea leaves Stoke job to focus on Republic of Ireland role
Rory Gallagher domestic abuse claims not pursued in courts 'due to lack of evidence'
Shane Dowling column: Credit to Clare - the Banner is clearly rising
Get the latest sports headlines straight to your inbox by signing up for free email alerts
