They did this despite a poor start, making an uncharacteristic number of errors throughout a match in which they were second best for considerable periods and looking less than assured in the endgame.
However, there was just enough of the real Munster to get them through. For while they spent a deeply uncomfortable ten minutes before half-time under serious pressure, they ultimately broke away to score an excellent try through Alan Quinlan to set them up for what looked like it may be a comfortable victory in the second period. The resilience, obduracy and timing was pure Munster.
During that first half, Munster had gotten off to a poor start, failing to nail the kick-off reception and ultimately conceding an excellent try to the equally excellent Ratuvou. Glen Jackson played intelligently throughout and his initial grubber for the Fijian winger was exquisite and had Munster in trouble from then on.
Munster responded, helped by a poor Gustard knock-on from the kick-off, and should have had a try almost immediately. In a superb season, Rua Tipoki won't reflect too fondly on the moment of hesitation that begat a forward pass with the line abegging. Back for the penalty and three points but it should have been more.
Tomas O'Leary had a very mixed game and some poor box-kicking allowed Saracens to re-establish territorial dominance. With a worrying couple of scrums thrown in, it was clear this wasn't going to be a procession. However, a couple of fierce hits by Howlett on de Kock and Tipoki on Haughton indicated Munster's mental resolve.
The pressure was lifted by a massive O'Gara penalty to touch before another chance was wasted when Mafi had the opportunity to pass but held on. However, a well-worked lineout tap sent O'Leary haring, his offload to Mafi who piled into Jackson. Quick ball ensured a mismatch when the Sarries defence didn't get organised in time. Powell left too much for Nick Lloyd to cover and O'Gara didn't need asking twice.
Nigel Owens did need to ask twice about the subsequent conversion - once his touch judges and then Derek Bevan, the TVMO. Suffice to say that O'Gara will have been mightily relieved they didn't concede a last-minute penalty to lose this one by a point.
If Howlett and Tipoki signalled Munster's resolve through their tackling, so too did Leonelli demonstrate Sarries' determination with a fearsome hit on Mafi. It was raw stuff.
An O'Connell lineout steal was a reminder of Chris Jack's absence, but the lineouts ended up as a score draw overall. While Munster had hairy moments in the scrum under pressure from Cobus Visagie, they survived that set piece intact as well.
Ironically, given the Munster tradition, when the rain came at half-time, it wasn't to the advantage of the men in red.
Once again, Munster erred on the kick-off with O'Gara uncharacteristically putting it out on the full. With Donncha O'Callaghan conceding a soft three points, the game was very much back on at 15-10.
A further three penalties conceded in the next eight minutes ensured territorial domination for Saracens, compounded by an O'Leary kick out on the full. Ratuvou threatened throughout and it was his break that led to Tipoki killing ball and ending up in the bin, with Jackson extracting another three points. Two points in it and a man down. All hands on deck.
Denis Leamy will have nightmares about the penalty he conceded in the endgame, but he will counter that his recklessness then should be balanced by his goading of Nick Lloyd to the point that the prop completely lost his composure amidst a flurry of punches. Leamy was happy to take them and the numerical balance was restored even if O'Gara missed the penalty chance.
When Cencus Johnston lay on the ball after the tackle, Munster's parlous position improved significantly. 18-13 and an extra man with 18 minutes left - surely now they would close it out. But Saracens refused to lie down and entered the last seven minutes just two points down at 18-16. A drop goal or penalty and Munster were out. If was all about field position.
Paul O'Connell talked earlier in the week about experience and how you only realise what it is when you have it. Munster had it in spades and you'd never back against them in this type of situation. They tackled their socks off and when they earned a penalty that saw them deep into the Saracens half with two minutes on the clock, there was a collective sigh of relief that could have been heard in Tipperary.
Then Leamy risked the farm with an intemperate step on the excellent Vyvyan and Saracens saw the chance being offered. Once again, it was all about field position and working the position for Jackson to drop the goal. Ironically, they patiently worked the position but got ahead of themselves and tried to go too far with ball in hand. A final penalty awarded against that magnificent old warhorse that is Richard Hill deprived Jackson of the shot at glory and a place in the final.
It was too nervy and error prone for this to be declared one of Munster's red letter days. It was fiercely fought but there will be some selection posers arising out of this for Kidney. Peter Stringer and Shaun Payne will have rekindled hopes. Paul O'Connell was named Man of the Match and played well, though I thought there was an argument for Alan Quinlan, despite his failure to nail Richard Haughton at the start of the Saracens try.
You know what Declan Kidney meant when he called this their cup final afterwards and his sentiments were right. Saracens were never going to be a soft touch, but they needed an awful lot to go right for them to beat Munster. Two yellow cards in the final quarter would not have found their way into the doctor's prescription. The upshot is that Munster now go into the final knowing that they have a lot to work on for what should be one of those seismic European days that they love so well. Perfect.