The opening score came in the 8th minute, from the home side, after a jinking Shane Williams forced Munster to concede a penalty inside their own 22 and after James Hook had opted for the five metre line-out, the Welsh star broke Donncha Ryan's tackle to score on the right, his conversion putting Ospreys seven points up.
Ryan made amends minutes later when he took a pass from Tomas O'Leary - whose superb break left the Ospreys defence for dead - and cut inside to score a try that originated in a crunching tackle from Brian Carney just inside the Ospreys half.
Hook had an opportunity to add to his side's total with a 26th minute penalty from 40 metres wide on the right that fell short but he had an easier chance three minutes later and made no mistake.
Munster looked in trouble in the 34th minute when Andrew Bishop broke clear and sent Sonny Parker hurtling for what looked a certain try only for Anthony Horgan to rescue the situation with a marvellous covering tackle. However, in the next phase, Munster were penalised again but referee David Changleng reversed the award and Manning cleared to half-way.
Williams once again spread havoc in the Munster defence, they were penalised again, lost Donncha O'Callaghan to the sin-bin and Hook tapped over the kick to leave his side eight points up at the break (13-5).
Munster: M Lawlor, B Carney, B Murphy, L Mafi, A Horgan; J Manning, T O'Leary; F Pucciariello, F Sheahan, T Buckley; D O'Callaghan, D Ryan; A Quinlan, J O'Sullivan, A Foley capt. Replacements: J Flannery, M Horan, S O'Connor, J Coughlan, B O'Meara, R O'Gara, K Earls.
Ospreys: S. Terblanche; J. Vaughton, S. Parker, A. Bishop, S. Williams, J. Hook, J. Spice; P. James, H. Bennett, C. Griffiths, B. Cockbain, AW. Jones, A. Lloyd (J. Thomas 3 mins), R. Jones, S. Tandy (R Pugh 3 min).