Fifteen points from the boot of Dan Biggar inspired the Ospreys to a first ever win at Thomond Park, putting the region into the driving seat for a home play-off semi-final.
The Ospreys had to survive a nervy final ten minutes with skipper Ryan Jones in the sin-bin, but a dogged defensive effort secured a well deserved win, the first by a Welsh region in Munster since 2004.
It was a surprisingly low-key Thomond Park at kick-off, and this was reflected in a very subdued start to the game as both sides struggled to get going. Indeed, this was typified by Munster fullback Paul Warwick as he struggled to find his distance for a few early touch-finders that flew straight out on the full.
It was the home side who struck first though, skipper Ronan O'Gara with a simple penalty in the 10th minute after Adam Jones was penalised for illegal binding in the scrum. The fly-half has an opportunity to extend the lead five minutes later after James Hook was caught offside, but the penalty struck the outside of the right hand post.
Clear chances were at a premium, but Munster then looked to carve their way through the Ospreys defence, O'Gara and David Wallace combining to create room for Warwick coming into the line. The fullback sidestepped his way past several challenges, only for Jerry Collins to halt his progress as the line beckoned.
With 23 minutes gone, Biggar levelled the scores with a penalty after Wallace was penalised for not releasing as Marty Holah worked hard at the breakdown. Munster should have been back in front just a couple of minutes later, only for O'Gara to fail with what seemed a relatively easy kick after Huw Bennett was penalised at the ruck. That miss was to prove costly, as with half an hour on the clock Biggar was handed a simple kick to give his side the lead after Alan Quinlan came in at the side of a ruck.
There was little by way of fluid rugby, with intense defence on top and both sides also making a number of unforced errors which prevented any real momentum building. However, it was the Ospreys who would have been the happier as the sides went in at half-time, Biggar's boot ensuring a narrow lead.
HALF-TIME: MUNSTER 3 OSPREYS 6
Biggar gave the Ospreys the perfect start to the second period, making it three out of three penalties to extend his team's lead to 9-3 within two minutes of the restart.
The young fly-half's confidence was up, and minutes later he opted to go for goal from near halfway after Quinlan was again penalised at the ruck, and his kick just had the legs to clear the crossbar, putting further distance between the teams.
Some good scavenging work at the breakdown by Andrew Bishop then allowed Biggar the chance to hack the ball forward and chase, O'Gara winning the race to ground the ball, carrying it over the line in the process. From the resulting five metre scrum, Collins picked and went, and when he was halted, Munster's James Coughlan was caught interfering on the floor and was sent to the sin-bin, Biggar continuing his fine form with the boot to make it 15-3.
Despite being minus a player, Munster looked to raise their game, and O'Gara then scored his second penalty of the night from a central position on the 10 metre line, before a powerful run from Lifeimi Mafi took his side deep into Ospreys territory, but there was to be no way through the visitors dogged defence on this occasion.
The Munster support were not enjoying what they were seeing, and were quick to get on the backs of the officials for every decision that went the Ospreys way. Right on the hour mark, O'Gara was given the opportunity to reduce the deficit further, but again, despite it looking kickable his radar was off and the ball came back off the upright to leave the score 15-6 to the Ospreys as Coughlan returned to the field.
The game was beginning to open up as Munster looked to create the opening that had so far evaded then, Mafi leading the way with a counter attack launched from inside his own 22, a move which ultimately ended in Biggar being bundled into touch. From the resulting lineout, Munster trundled forward ominously, and when the maul came to a halt, Ospreys skipper Ryan Jones was sent to the sin-bin for illegal interference.
Only sterling work from Holah, Biggar and Adam Jones prevented a close range try for Damien Varley, the trio holding him up as he crossed the line with the weight of the Munster pack behind him.
Mafi and Tom Gleeson then combined well to make good yardage, and when Gleeson was stopped just a few metres from the line, Peter Stringer recycled, feeding O'Gara who crashed over from close range. Once again, O'Gara had less success with his boot, leaving the score at 15-11 to the Ospreys with nine minutes remaining.
Munster were scenting victory, and awarded a scrum in Ospreys territory, they worked it yo their right before coming back across the field looking for the overlap, only for Tommy Bowe to halt their progress with a crunching tackle on Jean De Villiers.
With just a minute left the Ospreys defence was under intense pressure, but again they held up as Munster pounded on their line repeatedly, and with time running out, the hosts looked to move the ball quickly only to knock on. With the lock turning 80, from the scrum the Ospreys were able to clear to touch and claim a historic win.