Tony McGahan said his Munster side made too many basic errors as they pounded the Ospreys line in the closing stages in a bid to grab another dramatic late winner.
But, unlike their Heineken Cup exploits when Ronan O'Gara saved them with drop-goals against Northampton and Castres, they were unable to conjure up a last-gasp winner this time having left themselves with too much to do.
A dreadful third quarter saw Munster six points adrift going into the closing stages, but McGahan said they had only themselves to blame for not completing the job.
"We set up the opportunity to take it in the end but couldn't finish the job," said McGahan. "We put ourselves in a good position late on but through our own inaccuracy we just didn't finish the deal."
And their miserable night was completed when Doug Howlett was carried off with what seemed like a serious Achilles injury, which looks certain to keep him out of the trip to play Scarlets in the Heineken Cup this weekend with early speculation suggesting that he may not return before the new year.
Munster led 10-6 at the interval after an opening half that neither side dominated, and kickers Ian Keatley and Matthew Morgan both missed a pair of penalties they would normally land.
Morgan and Keatley exchanged penalties before Munster got a break. A grubber from Will Chambers took a deflection off Jonathan Thomas inside the '22' and Howlett reacted quickest to race in and touch down, with Keatley adding the points to make it 10-3 after 28 minutes.
Morgan pulled back another penalty six minutes from the break to leave it 10-6 at the interval.
The damage was done to Munster after the restart as Ospreys took over. They hit the front four minutes after the break when a break by Ian Gough was finished by Richard Fussell, and referee Peter Allan went to the TMO and rightly ruled that a pass from Rhys Webb was touched by Keatley and not the Ospreys full-back Barry Davies.
Munster were then caught napping when scrum-half Webb tapped a quick penalty inside the 22 and went round Tomas O'Leary and Simon Zebo to touch down for the sort of try Munster rarely concede.
There was another let-off when Morgan missed his second conversion, and Tony McGahan drafted in Paul O'Connell, Ronan O'Gara and Wian du Preez.
O'Gara reduced the deficit after 62 minutes with a penalty, but Ospreys restored their six-point lead from the restart when Niall Ronan was penalised for hands in the ruck and Morgan landed the 40-metres effort to make it 19-13.
Munster piled on the pressure after that but this time could not create another late winner.
Ospreys -- B Davies (H Dirksen 48); T Bowe, A Bishop, A Beck, R Fussell; M Morgan, R Webb (T Isaacs 66); D Jones, R Hibbard (M Davies, 57), A Jarvis (C Griffiths, 48); I Gough, J Thomas; T Smith, J King, J Bearman.
Munster -- D Hurley; D Howlett (J Murphy 76), W Chambers, D Barnes (R O'Gara, 50), S Zebo; I Keatley, T O'Leary (C Murray 61); M Horan (W du Preez 50), D Varley, BJ Botha; D O'Callaghan, D Ryan (P O'Connell 45) ; D Leamy (J Coughlan 61), N Ronan, P O'Mahony.
REF -- P Allan (SRU).