Peter Stringer's opportunistic try proved the difference as Munster held on for a thrilling win at the Ospreys.
HEINEKEN CUP POOL 4
Ospreys: (12) 18:
Pens: Henson 6.
Munster: (9) 20:
Pens: O'Gara 5.
Penalty kicks dominated the game as Munster fly-half Ronan O'Gara and opposite number Gavin Henson carried out their own personal duel.
But just after half-time, scrum-half Stringer darted over in the corner from an attacking five-metre scrum.
The Ospreys gained a bonus point in defeat but it was a small consolation for a damaging home loss at The Gnoll.
Opportunities for the backs to show their stuff were few and far between in the opening quarter, as the two packs grunted and strained for superiority.
Ospreys fly-half Henson and opposite number O'Gara matched each other in the tactical kicking as the pair went through their considerable repertoires.
But Henson gave the Neath-Swansea side a 9-6 edge with 20 minutes gone, converting all three of his penalty kicks while O'Gara could only manage two from his three.
The Ospreys were reduced to 14 men soon after when wing Richard Mustoe was sent to the sin bin for stamping on the head of Munster prop Marcus Horan.
Horan left the pitch with blood streaming down his face, although he was patched ready for the second half.
Mustoe, who could easily have been shown a red card, will be fortunate if he escapes a citing for the incident.
Despite being a man light the Ospreys fashioned two more penalty attempts for Henson, only for his previous accuracy to desert him.
Just as Mustoe was preparing to return, Munster incurred the wrath of French referee Joel Jutge for hands in the ruck and Jim Williams was shown yellow.
Henson potted the resulting penalty from in front of the posts to open up a six-point lead, but O'Gara pulled one back in first-half injury time to make it 12-9 to the home side at the break.
Munster finally broke through for a try five minutes after the restart, after a terrible pass from Ospreys scrum-half Jason Spice left Henson with no option but to concede a five-metre scrum.
Stringer shaped to pass from the base of the Munster scrum, but instead the Ireland scrum-half darted untouched down the blindside for an unconverted try.
Henson and O'Gara exchanged penalties, but the Ospreys found themselves down to 14 men again after 60 minutes when centre Elvis Seveali'i was sin-binned for a high tackle on John Kelly.
Another exchange of penalty kicks saw Munster holding a slender 20-18 lead going into the last 10 minutes, setting up a tense and exciting finale to the match.
The Ospreys camped down in the Munster half but the visitors produced a series of magnificent defensive actions to hold off the Welsh attacks.
As the clock ticked into injury time, Munster at last lifted the siege and O'Gara's boot sent the ball spiralling 60 yards upfield.
The Ireland fly-half was just wide with a snap drop-goal as he tried to kill off the game, but the miss was incidental as the Ospreys remained pinned in their own half.
Neath Swansea Ospreys: A Durston; R Mustoe, S Parker, E Seveali'i, S Williams; G Henson, J Spice; D Jones, B Williams (capt), A Jones, A Newman, B Cockbain, J Bater, S Tandy, R Jones.
Replacements: M Davies, P James, L Tait, L Bateman, R Pugh, A Williams, M Jones.
Munster: C Cullen; J Kelly, S Payne, R Henderson, A Horgan; R O'Gara, P Stringer; M Horan, F Sheahan, J Hayes, D O'Callaghan, P O'Connell, J Williams, D Wallace, A Foley (capt).
Replacements: J Flannery, G McIlwham, T Hogan, A Quinlan, M Prendergast, P Burke, M Lawlor.
Referee: Joel Jutge (France)