Ulster's Pro12 winning streak came to an end in Swansea on Sunday as they went down 32-14 to the Ospreys at Liberty Stadium.
Ospreys bounced back from the concession of an early try to maintain their winning start to the season.
Ospreys had battled to victory in Italy against Treviso a week earlier, while Ulster were fresh from a comfortable win over Cardiff.
The Irishmen got off to the perfect start when Paddy Jackson made an eye-catching break through a gaping hole in the home defence to score, before picking himself up and adding the conversion.
The rest of the half, however, belonged to Ospreys. Dan Biggar was once again in prolific form with the boot, kicking four penalties before the interval to cancel out the deficit and send the Welsh side in at half-time 12-7 to the good.
Ulster's indiscipline through the match cost them dearly, with referee Dudley Phillips making his presence felt with the whistle on numerous occasions, and pinning the visitors back.
The first points of the second half came on 48 minutes when Biggar added his fifth penalty of the afternoon, and on the hour mark Ospreys were awarded a penalty try after Ulster had been guilty of successive scrum infringements.
Another penalty, following the successful conversion, from Biggar put Ospreys 25-7 up with 15 minutes remaining.
Richard Fussell then put the result beyond doubt when he followed his own kick through the Ulster defence to touch down and, though the visitors were awarded a late penalty try when referee Phillips adjudged that Ospreys had collapsed a maul, there wasn't enough time for a comeback.
Tries: Fussell, Penalty try
Cons: Biggar, Morgan
Pens: Biggar 6
Tries: Jackson, Penalty try
Cons: Jackson, McKinney
Yellow cards: Hibbard (Ospreys - 19th min); Diack (Ulster - 48th)
Ospreys: 15 Barry Davies, 14 Richard Fussell, 13 Tom Isaacs, 12 Andrew Bishop, 11 Hanno Dirksen, 10 Dan Biggar, 9 Rhys Webb, 8 Jonathan Thomas, 7 Justin Tipuric (C), 6 Tom Smith, 5 James Goode, 4 Ian Gough, 3 Aaron Jarvis, 2 Scott Baldwin, 1 Duncan Jones.
Replacements: 16 Richard Hibbard, 17 Cai Griffiths, 18 Joe Rees, 19 James King, 20 Joe Bearman, 21 Matthew Morgan, 22 Sonny Parker, 23 Kristian Phillips.
Ulster: 15 Jared Payne, 14 Craig Gilroy, 13 Luke Marshall, 12 Nevin Spence, 11 Ian Whitten, 10 Paddy Jackson Ian Humphreys, 9 Paul Marshall, 8 Robbie Diack, 7 Chris Henry, 6 Pedrie Wannenburg, 5 Dan Tuohy, 4 Lewis Stevenson, 3 Jerry Cronin, 2 Andy Kyriacou, 1 Declan Fitzpatrick.
Replacements: 16 Nigel Brady, 17 Paddy McAllister, 18 Adam Macklin, 19 T Barker , 20 Willie Faloon, 21 Blane McIlroy, 22 James McKinney, 23 Adam D'Arcy
Venue: Liberty Stadium
Referee: Dudley Phillips (IRFU)