Munster's winning run at the start of the United Rugby Championship came to an end at the hands of Ospreys in Wales.
Johann van Graan’s side had won their last eight meetings with the Welsh region but were decidedly second best throughout at the Swansea.com Stadium.
Ospreys out-half Stephen Meyler kicked six from six, with Munster’s Craig Casey getting the only try of the game.
Munster conceded 14 penalties and never got to grips with the Ospreys tenacity in defence.
A failure to get a bonus point sees Munster sit in third in table ahead of the international break, five points behind Leinster on 24.
Offaly native Jack Regan made his Ospreys debut, the lock coming on in the 68th minute to help see out the victory.
"They seemed to be off mentality and physically," was the verdict of former Munster scrum-half Peter Stringer on analyst duty for RTÉ Sport.
The visitors made 12 changes to the team that accounted for Connacht last week and while a number of Ireland internationals were rested, Peter O'Mahony, Tadhg Beirne and Casey were all included and there was a seasonable debut start for Jack Crowley at out-half.
Making their first club appearances since the Lions series, Conor Murray and Damian de Allende also came off the bench but added little to the threat.
The hosts, meanwhile, had to do without five Wales players, including captain Alun Wyn Jones, who are in national camp preparing for next week’s game against New Zealand.
The first half was a stop-start affair, the highlight of which was a super spot by the television match official Mike Adamson.
No tries in Swansea as Ospreys lead Munster 9-3 at half-time. Niall Scannell did touch the ball down but Tadhg Beirne was obstructing the hosts' defence | Live updates: https://t.co/JinFpjyqCE Watch #URC live on @RTE2 and @RTEPlayer pic.twitter.com/HM5bSvbaBs— RTÉ Rugby (@RTErugby) October 23, 2021
Munster looked to have scored the opening try but the eagle-eyed official saw an obstruction in the lineout before Niall Scannell’s touchdown.
Prior to that, Meyler and Crowley had swapped early penalties but neither side could build enough pressure to dominate.
On 32 minutes Jack O’Donoghue knocked on and then went off his feet in a phase of play that allowed Meyler to add another penalty, while referee Hollie Davidson reversed a penalty four minutes later after Munster had pushed the Ospreys off their own ball at a scrum.
Meyler, this time from a more difficult angle, pushed the lead out to six points, while a late Munster attack came to nothing.
It didn’t take long for Meyler to extend the advantage, popping over a penalty from distance just five minutes into the second half after John Ryan was penalised at a scrum.
TRY! A long winding Munster maul is finished off by Craig Casey and the converted try takes the Irish province within two points of Ospreys | Live updates: https://t.co/HEelmPT9gB Watch live on @RTE2 and @RTEPlayer #URC #OSPvMUN pic.twitter.com/LZONgKgpiT— RTÉ Rugby (@RTErugby) October 23, 2021
The only try of the game came in the 54th minute via a lineout maul, Casey on hand to dot down following a 20-yard drive, with Crowley adding the extras.
That reduced the margin to two points but Meyler was in super form off the tee, and punished repeated Munster infringements with two further penalties.
Replacement Ben Healy almost secured a losing bonus point but two late long-range shots were off target.
Ospreys: Max Nagy; Alex Cuthbert, Owen Watkin, Keiran Williams, Mat Protheroe; Stephen Myler, Rhys Webb (capt); Nicky Smith, Elvis Taione, Tom Botha; Bradley Davies, Rhys Davies; Sam Cross, Jac Morgan, Ethan Roots.
Replacements: Ifan Phillips, Gareth Thomas, Rhys Henry, Jack Regan, Morgan Morris, Reuben Morgan-Williams, Joe Hawkins, Dan Evans.
Munster: Matt Gallagher; Andrew Conway, Liam Coombes, Dan Goggin, Shane Daly; Jack Crowley, Craig Casey; Jeremy Loughman, Niall Scannell, John Ryan; Jean Kleyn, Fineen Wycherley; Tadhg Beirne, Peter O'Mahony (capt), Jack O'Donoghue.
Replacements: Kevin O'Byrne, Josh Wycherley, Keynan Knox, Gavin Coombes, John Hodnett, Conor Murray, Ben Healy, Damian de Allende.
Referee: Hollie Davidson (SRU).