Munster's defence of their Celtic League title is looking shaky after a second consecutive loss to a Welsh side.
Full-back Gavin Henson, unwanted by Wales coach Steve Hansen, thumbed his nose at the national selectors with a superb performance in the Neath-Swansea Ospreys' nail-biting 33-26 victory at the St Helen's ground in Swansea.
The brilliant 21-year-old was solid in defence, powerful in attack and slotted goals from all over the place as he took advantage of a Munster side missing 13 first-choice players on World Cup duty.
Ahead 23-12 at half-time, the Ospreys were in control for much of the match, scoring tries at regular intervals to keep the visitors at bay. A late try to Munster full-back Jeremy Staunton - his second of the match - narrowed the margin to seven points, and the 5,000-strong crowd had to survive eight minutes of injury time as the Irish side pressed for the equalising try.
Munster opened the scoring when the home side fell for a Staunton dummy and the visiting No 15 jogged in under the posts. It was Munster's first try of the Celtic League season after 184 barren minutes of rugby.
It did not take long for the Ospreys to hit back. Fly-half Shaun Connor produced a pinpoint kick to the corner and wing Dave Tiueti climbed above opposite number Mossie Lawlor to palm the ball down to centre James Storey for the try.
Minutes later Tiueti ran over the top of Lawlor to score in the right-hand corner, and Henson's sideline conversion gave the Ospreys a deserved 17-7 lead. Henson added another penalty goal, but Munster came back into the match when unwanted Ireland flanker David Wallace took advantage of a three-man overlap to score.
Home scrum-half Andy Williams brought the crowd to their feet early in the second half when he stole the ball out of the back of the Munster scrum and scampered 25 metres unopposed for the Ospreys' third try. Henson's conversion gave his side an 18-point lead and Munster a mountain to climb.
They tried. Veteran centre Mike Mullins came back on the angle from close range to power over and Staunton's conversion narrowed the gap to 11 points on the hour.
The Ospreys were made to sweat when Mullins and Staunton produced a piece of midfield magic for the latter's second try, but Henson's huge punts kept his side out of trouble as the clock ran down.
Neath-Swansea: G Henson; D Tiueti, J Storey, S Gibbs (capt), E Seveali'l; S Connor (A Durston, 62), A Williams; P James, B Williams, A Millward, A Newman, L Tait (L Bateman, 44), G Thomas, J Bater (S Tandy, 62), N Bonner-Evans.
Munster: J Staunton; M Lawlor, M Mullins, J Jones-Hughes, S Payne; C O'Sullivan (D Crotty, 70), E Reddan; S Kerr, J Flannery, M Cahill (J Danaher, 60), E Halvey (C McMahon, 81), D Pusey, D Leamy (T Hogan, 46), D Wallace, J Williams.
Referee: Rob Dickson (Scotland).Reuse content