Anthony Foley capped his last home appearance for Munster with a try but Glasgow Warriors failed to read the Musgrave Park script as they beat the Heineken Cup finalists with a stirring display.
However it was a controversial try that provided Glasgow with their match-winning score.
There were doubts about whether Thom Evans had successfully grounded the ball for his 68th-minute try, while Munster were also incensed by a clear case of obstruction in the build-up to it.
Dan Parks’ brilliant conversion from the left touchline put the Scottish side 21-13 in front and despite a furious finish from Munster, which included an unconverted Paul O’Connell try, the visitors clung on for the win.
Two of Munster’s greatest servants lined up for their final home match with the province – number 8 Anthony Foley captained the team in his 201st competitive game and newly appointed Ireland coach Declan Kidney took his usual spot in the stand.
But there was no room for sentimentality with an in-form Glasgow outfit in town.
They were hunting for their fifth straight league win – something the club had not achieved since the 2001/02 season – and they foraged into a 14-0 lead.
Munster dominated possession in the early stages but perhaps with the Heineken Cup final in mind, they lacked their usual precision particularly at the breakdown where John Barclay and Johnnie Beattie both impressed.
Glasgow looked the hungrier and on the balance of play, their 17th-minute try was a deserved one.
There was a touch of good fortune about it though as a Colin Gregor kick bounced horribly away from the retreating Denis Hurley, leaving the Munster full-back on the turf, Gregor gathered and ran into space before putting Lome Fa’atau in close to the posts.
Parks added the conversion and Glasgow crossed the Munster line again, six minutes later.
There was a breakdown in communication between Ian Dowling and Foley when the latter called a quick lineout, and the winger’s feed was gleefully intercepted by Warriors hooker Dougie Hall who bounded over for his first try of the season.
Munster then roused themselves to score 13 unanswered points before half-time. Glasgow lost some momentum when prop Moray Low went off with an ankle injury and the hosts took control.
In the 33rd-minute, number 8 Foley was spotted by Peter Stringer as he lurked on the blindside and he had the wherewithal to avoid a collision with touch judge Alan Rogan, who was standing just inside the touchline, and pile over in the left corner.
O’Gara converted and he also kicked two out of four penalty attempts in first half injury-time as Glasgow’s discipline began to let them down, most notably when flanker Barclay was sin-binned for a high tackle on Keith Earls.
The numbers were evened up early in the second half when Munster centre Rua Tipoki saw yellow for a dangerous challenge on Parks, who missed the resulting penalty kick.
With Foley going off to a rapturous reception, Glasgow kept a stubborn hold of their 14-13 advantage.
Munster had a try ruled out in the 57th-minute – replacement David Wallace thought he had scored but the effort was scratched out for interference from Paul O’Connell.
The game’s major talking point arrived ten minutes later. As Glasgow attacked on the left, Earls was clearly obstructed by James Eddie from getting a tackle in.
Munster looked to referee James Jones for a whistle but it never came and Evans won the race to his own grubber kick to score.
Television match official Trevor Collins ruled that Evans had successfully squeezed over in the left corner. Munster saw red but all they could muster in reply was O’Connell’s 80th-minute effort – an American football-style dive for the line off the back of a ruck.