In what was an epic match that lived up to its pre-weekend status as the game to watch in Round One of the 2011/12 Heineken Cup, it took an 83rd-minute drop goal from Ronan O'Gara to finish off 42 phases of play and break Saints' hearts in the process.
Mallinder may have praised his players post-match, but his frustration was also clear at the consistency of the refereeing. One such instance actually set Munster on their way to their match winning score; a powerful rolling maul seeming to attract several men in red into joining from an offside position, but which instead was ruled as being held up and therefore giving the hosts the scrum from which they started their march upfield.
So while the Saints and their 1,800-strong band of travelling supporters left Thomond Park disappointed by the result, there was still plenty of pride that twice the team came back from seven-point deficits early in each half to be in with a chance of winning the contest.
Munster may have got off to the best possible start, but they would have been thanking Saints for their generosity in creating the opportunity. Having defended really well in midfield and turned the ball over, a crucial fumble gave Denis Hurley the chance to kick ahead and force Ben Foden to concede a lineout five metres out.
The lineout was secured, the maul rolled inexorably towards the line and Damien Varley emerged with the ball and the rapturous reception of the Thomond Park crowd ringing in his ears. Ronan O'Gara nailed the conversion and with only three minutes on the clock Saints already had something of a mountain to climb.
But if there were any nerves they didn't show. Ryan Lamb was looking lively and one break in particular had Munster scrambling.
The Saints back three had been built up by the Irish media in the run-up to the game, and all played a crucial role in creating and scoring a vital try. Vasily Artemyev began the move running from deep before finding Chris Ashton with the offload off the deck. The wing in turn sent Ben Foden clear down the left wing before looping to create a two-on-one. Foden timed his pass superbly and Ashton was over in the corner.
Lamb, whose earlier penalty shot had dropped just under the bar, made no mistake with the conversion and Saints were back on level terms.
This didn't last long, Lamb sending his second penalty through the sticks for a 10-7 lead, and all of a sudden the 26,000 crowd knew they had a game on their hands. And if there was any doubt that Saints had to keep the error rate to an absolute minimum it was erased when an offside on half-way almost handed Munster a second try.
Calum Clark's intentions were honourable, but there was no doubt he had committed an offence, and when O'Gara sent the kick to the corner the red pack set up another maul. This looked dangerous enough as it was, but when Niall Ronan broke off the back to put Conor Murray over Munster seemed to have a second try.
Referee Nigel Owens had other ideas, calling play back for a forward pass, and when Saints turned on the power to win a penalty at the subsequent scrum there was a massive sigh of relief from the travelling members of the Saints Nation in the stands.
Having been let off the hook, Saints went further in front with a Lamb penalty and there were plenty of promising signs for the men in black, green and gold. The scrum was going well and whenever the ball went wide something looked likely to happen.
But Munster remained dangerous, too, and when O'Gara slipped a grubber into the in goal area with six minutes to go in the half TMO Derek Bevan was called into action for the first time. No one had touched the ball and a 22-metre kick was the result, but the play had shown that the hosts should never be ruled out on their home turf.
Then having done so well, Saints conceded crucial points in the last two minutes of the half. Ironically enough the first three of these, an O'Gara penalty, came from a Lamb kick which had cruelly bounced infield and over the dead ball line. The scrum was on the Saints' 10-metre line and when Soane Tonga'uiha was penalised O'Gara stepped up to slot the kick.
Worse came in injury time. Munster's midfield option runners were doing a good job of marshalling the Saints' defenders, and when a hole opened up in front of Doug Howlett in the visitors' 22 the former All Black strolled through and over the whitewash. And with O'Gara's conversion it meant that instead of going in ahead, the Saints were now four points down at half-time, scant reward for their hard work.
Replays at half-time showed that there had been a fumble at the ruck immediately before Howlett's try, and Saints certainly needed the rub of the green in the second half if they were going to get the win they wanted.
Unfortunately, as they had done in the first half, instead of scoring first Saints conceded the opening points after play resumed. No one claimed the kick off, and when Clark instinctively caught the rebound from Artemyev it gave O'Gara the chance to extend the lead to seven, which he duly did.
Lamb replied almost immediately from a virtually identical offence, BJ Botha catching Johne Murphy's fumble, and at 20-16 with half-an-hour to go there was everything to play for.
Saints still needed to take their chances, and when Lamb's ambitious kick to touch from a penalty fell infield it looked like a crucial opportunity had gone. Then all of a sudden Saints had something go their way. Lamb went on a jinking run and when his pass rebounded off O'Gara play went on and James Downey was over for the try.
The wind had now picked up, which made the conversion attempt very difficult, and though Lamb's kick went left of the uprights Saints nevertheless had a 21-20 lead with a quarter of the match remaining.
It increasingly looked like a mistake one way or the other was going to decide the match, and when Artemyev made his first offensive mistake of his Saints career with the line at his mercy Munster had received a massive let off. It was a difficult chance, the Russian hacking ahead an Ashton pass before being beaten by the bounce, but it was a great opportunity nonetheless. Indeed, the pressure was growing on both teams, so much so that even O'Gara started missing from the tee.
But when the crucial moment came fully three-and-a-half minutes after time had expired there was to be no such mistake and Thomond Park erupted with delight and relief.
REFEREE Nigel OWENS
3mins MUNSTER Try Varley Con O'Gara 7-0
7mins SAINTS Miss pen Lamb
9mins SAINTS Try Ashton Con Lamb 7-7
13mins SAINTS Pen Lamb 7-10
21mins SAINTS Pen Lamb 7-13
39mins MUNSTER Pen O'Gara 10-13
40mins MUNSTER Try Howlett Con O'Gara 17-13
HALF-TIME MUNSTER 17 SAINTS 13
42mins MUNSTER Pen O'Gara 20-13
45mins SAINTS Pen Lamb 20-16
57mins SAINTS Try Downey 20-21
71mins MUNSTER Miss pen O'Gara
80mins MUNSTER DG O'Gara 23-21
FULL-TIME MUNSTER 23 SAINTS 21