Eric Elwood is giving youth a fling in his final season with Connacht, but a workmanlike performance at Liberty Stadium was undermined by simple errors.
The five-time champions ruthlessly punished those mistakes and took all five points as Connacht left Swansea without the consolation of the bonus point they deserved. Connacht have now lost on all eight visits to this venue but they would have felt a bonus point was within reach.
They had a chance 15 minutes from time when trailing 19-9, but Dan Parks was narrowly off target with a penalty from just inside halfway. From there to the end they were on the back foot as the champions came in search of their first try bonus point of the campaign.
A couple of penalties to the corner failed to crack the Connacht defence, but once again it was an error that gave the Ospreys the opening they needed when they were penalised on their put-in in a scrum inside their own '22' and scrumhalf Kahn Fotuali'i reacted quickest to tap and squirm over.
Elwood has not been afraid to give youth a chance this season, with 19-year-old Darragh Leader the latest to make his debut yesterday, and the youthful Connacht defence needed to be organised and disciplined to deal with an early onslaught.
Initially, they dealt with everything that came their way, but then 20-year-old local Eli Walker again illustrated why many regard him as Shane Williams' successor as he looped around and jinked his way over for a 15th-minute try.
Dan Biggar added the difficult conversion from the right, but the Connacht response to the try was good and two penalties from Parks reduced the deficit to 7-6.
However, Connacht's hopes went by the wayside either side of the interval when first Ospreys full-back Richard Fussell timed his run perfectly to crack the visitors' defence and Justin Tipuric was on his shoulder to score an unconverted try in the right corner to leave them 12-6 in front at the interval.
Worse followed two minutes after the restart when Jonathan Thomas intercepted a pass from Parks to score from 35 metres and open up a 19-6 lead.
Parks brought Connacht within range of a bonus point with a penalty after 52 minutes.
But then the league's all-time top scorer was narrowly off target with a penalty from inside halfway 15 minutes from time, but that was as close as Connacht came to getting something from the game as Ospreys upped their effort in search of a fourth try, although a couple of penalties to the corner failed to crack the visitors' defence.
Once again it was a Connacht error that gave the champions the opening they needed for the bonus point when they were penalised on their put-in in a scrum inside their own 22.
Ospreys' Fotuali'i reacted quickest to tap and squirm over, with Biggar adding the conversion to bag all five points when Connacht should have got something from the game.
They did not score a try for the second successive league game and will need to defeat Benetton Treviso at home next weekend to stop the slide.
Scorers -- Ospreys: Walker, Tipuric, Thomas, Fotuali'i tries, Biggar 3 cons. Connacht: Parks 3 pens.
Ospreys: R Fussell (M Morgan 78); H Dirksen, A Bishop, A Beck, E Walker; D Biggar, K Fotuali'I (R Webb 78); R Bevington (D Jones 50), R Hibbard, A Jones; A-W Jones (capt), I Evans (J King 50); J Bearman, J Tipuric, J Thomas.
Connacht: D Leader; T O'Halloran, R Henshaw, M Fifita (D Poolman 31), F Vainikolo; D Parks (M Nikora 67), K Marmion (D Moore 50); B Wilkinson (R Ah You 57), J Harris-Wright (A Flavin 62), N White (capt) (R Loughney 67); M Swift, G Naoupu (D Gannon 38); J Muldoon, W Faloon (J O'Connor 50), E McKeon.
Referee: G Clancy (IRFU).