The Ospreys kept alive their Heineken Cup quarter-final hopes after Dan Biggar booted Munster to defeat in Swansea.
Biggar produced an immaculate goal-kicking performance, landing four penalties and a conversion of Wales scrum-half Mike Phillips' try as the race for Pool Three domination remained wide open.
Munster shaded the try-count through touchdowns from prop Tony Buckley and centre Keith Earls, while Ronan O'Gara added a penalty and conversion, but the Irish heavyweights were floored up-front.
They had no answer to a mighty Ospreys scrum and the efforts of front-row trio Paul James, Richard Hibbard and Adam Jones, with Buckley and loosehead Wian Du Preez suffering a torrid time.
The group now heads towards a potentially thrilling climax next month with two final rounds of pool matches, and Ospreys, Munster and Toulon all hotly contesting top spot.
Biggar's mature contribution shone in the heat of battle, a feisty contest that occasionally threatened to boil over, but ultimately produced another high-octane encounter that has become a Heineken Cup trademark.
The Liberty Stadium's undersoil heating did its job, ensuring a game pivotal to both sides' quarter-final hopes went ahead despite South Wales being blanketed by heavy overnight snowfall.
Ireland wing Tommy Bowe moved into midfield for the Ospreys, replacing Wales centre Andrew Bishop, while Munster were unchanged following last weekend's 22-16 win against their hosts in Limerick.
One notable absentee though from the Munster match-day squad was lock Paul O'Connell, ruled out through suspension after being sent off six days ago.
Munster made the early running in terms of territory and possession, with O'Gara kicking a penalty, but the Ospreys showed signs of scrummaging dominance when they shunted their opponents backwards.
It resulted in a flare-up involving several players and led to French referee Romain Poite handing out a warning to rival skippers Alun-Wyn Jones and Denis Leamy.
Biggar landed an equalising penalty after 16 minutes, but Munster then claimed the game's opening try when they capitalised on poor Ospreys defensive work.
Centre Sam Tuitupou blew apart the initial defensive line, before Leamy took it on at pace and giant prop Buckley rumbled over between the posts.
O'Gara converted, yet the Ospreys did exactly what they needed to do by responding with a try of their own just four minutes later.
Slick passing at pace took the Ospreys deep into opposition territory, before Phillips showed his trademark power from close range to touch down under a pile of bodies, although Poite required confirmation from the television match official.
Biggar's conversion tied it up at 10-10, before his second penalty edged Ospreys ahead, securing a narrow interval advantage their set-piece authority merited.
Munster began the second period by exerting sustained pressure inside the Ospreys 22, and it took a mighty defensive effort to repel wave after wave of red-shirted attackers.
Ospreys' tacklers were up to the task though, initially clearing their lines through turnover ball and then gaining a penalty after Munster lock Mick O'Driscoll ran aggressively through an inviting midfield channel.
As if to underline Munster's points-scoring failure, Biggar rifled over a superb long-range penalty that made it 16-10, but just when the Ospreys looked as if they might have weathered the storm, back came their opponents.
A touch of class by former New Zealand Test wing Doug Howlett saw him chip the ball exquisitely over Ospreys' defence, and Earls accepted a kind bounce and sprinted in for his team's second try. O'Gara saw his conversion attempt bounce back off the post, but Earls' score guaranteed a tense, tight final quarter.
Another Biggar penalty sealed the deal, but Munster thwarted relentless late Ospreys pressure to keep hold of what could prove a priceless losing bonus point. And there was further evidence of the game's powder-keg nature after the final whistle when O'Gara and Phillips heatedly exchanged words.
Ospreys: B. Davies (Bishop 77), N. Walker, Bowe, Hook, Fussell, Biggar, M. Phillips, James (D. Jones 65), Hibbard, A. Jones, R. Jones (Gough 65), A. Jones, Collins, Holah, Thomas.
Munster: Warwick, Howlett, Earls, Tuitupou (Mafi 66), J. Murphy, O'Gara, O'Leary (Stringer 55), du Preez, Varley, Buckley (J Hayes 53), D. O'Callaghan (D. Ryan 70), O'Driscoll, Coughlan (Quinlan 55), Wallace, Leamy.
Referee: Romain Poite (France) ..