Ospreys came from behind to beat Munster 17-13 in the battle of the top two in the RaboDirect Pro12 at Thomond Park in Limerick.
The win means Ospreys remain top of the standings and Munster have now suffered their second consecutive defeat.
Munster hadn't lost at home since April 2010 when the same Welsh visitors beat them 15-11, but too many basic errors cost the Irish side the points.
The home side got off to a dream start, and found themselves 7-0 up within the first three minutes.
Danny Barnes managed to block down an Osprey's clearance kick, and dived over for the first try of the game, Ian Keatley adding on the extras.
Ospreys responded well though, and Dan Biggar kicked a penalty for them a few minutes later for their first points.
They had chances to take the lead throughout the first half as they began to dominate, but a series of knock-ons and handling errors prevented them from getting over the try line.
Munster made it a seven point game midway through the first half, Ian Keatley converting a penalty, but after that, neither side made much impression on the scoreboard before the break, with Dan Biggar's penalty for Ospreys right on the half time whistle the only other score.
Biggar kicked a penalty straight after half time to leave a point in it, as Ospreys picked up where they had left off.
Justin Tipuric was sin-binned for Ospreys soon after though, and the away side clearly struggled without their captain for the next ten minutes.
They didn't let that setback affect them though, and they scored a try midway through the half, after a breakaway saw Rhys Webb dive over, after a poor Mick O'Driscoll pass was intercepted.
Keatley put a point between them with a placed kick for Munster as things became a little more heated, but Munster just couldn't find another score, and Dan Biggar ensured the win for Ospreys with a last minute penalty.
Pens: Keatley 2
Pens: Biggar 4
Yellow card: Tipuric
Munster: 15 Johne Murphy, 14 Doug Howlett, 13 Danny Barnes, 12 Lifeimi Mafi, 11 Denis Hurley, 10 Ian Keatley, 9 Duncan Williams, 8 Peter O'Mahony (c) 7 Niall Ronan, 6 Dave O'Callaghan, 5 Mick O'Driscoll, 4 Billy Holland, 3 Stephen Archer, 2 Denis Fogarty, 1 Wian du Preez.
Replacements: 16 Sean Henry, 17 Marcus Horan, 18 BJ Botha, 19 Ian Nagle, 20 Tommy O'Donnell, 21 Peter Stringer, 22 Scott Deasy, 23 Simon Zebo.
Ospreys: 15 Barry Davies, 14 Hanno Dirksen, 13 Tom Isaacs, 12 Andrew Bishop, 11 Richard Fussell, 10 Dan Biggar, 9 Rhys Webb, 8 Jonathan Thomas, 7 Justin Tipuric (c), 6 Joe Bearman, 5 Ian Evans, 4 Ian Gough, 3 Cai Griffiths, 2 Richard Hibbard, 1 Duncan Jones.
Replacements: 16 Mefin Davies, 17 Aaron Jarvis, 18 Joe Rees, 19 Tom Smith, 20 James King, 21 Matthew Morgan, 22 Sonny Parker, 23 Kristian Phillips.
Venue: Thomond Park
Referee: James Jones (Wales)