Replacement Jamie Nutbrown was the hero for the visitors when he broke through for the game’s only try after Connacht had initially repelled a forward drive. His fellow replacement Matthew Jarvis slotted the conversion, giving the Ospreys the lead for the first time and victory on the night.
Connacht had the opportunity to snatch victory at the death, but Miah Nikora’s touchline penalty kick dipped under the crossbar, denying the home side only a second ever win over the Ospreys in the league history.
Until Nutbrown’s try, the hosts had held a 15-9 lead, despite losing Bernie Upton to the sin bin and being on the wrong end of the penalty count.
They had also enjoyed the better of the opening exchanges, particularly at scrum time, which had laid the platform for first-phase possession and territorial control.
Three penalties from former New Zealand U21 out-half Nikora, including a beauty from the left touchline, helped them surge ahead 9-0 inside 18 minutes.
But Ospreys’ teenage out-half Matthew Morgan was on target with his penalties on 21 and 36 minutes to reduce the deficit, before the Magners League debutant dropped a goal to level matters.
Connacht had Bernie Upton yellow-carded six minutes into the second half but looked well placed to secure the win with those two further penalties by Nikora.
However, they failed to close out the game and the Ospreys, needing seven points to win, made the most of a final penalty opportunity to kick for touch.
Although they found no way through their forwards, some slick handling allowed Nutbrown to stride over from 10 metres out, with Jarvis’ extras sealing the win.
Connacht coach Eric Elwood admitted that a bonus point was no consolation for his side, having targeted a victory.
He said: “We lacked the usual intensity at the breakdown and, even as bad as we played, to be six points up near the end and not to close the game out was very disappointing.”
Scorers for Connacht: M Nikora 5 pens.
Scorers for Ospreys: J Nutbrown try; M Morgan 2 pens, drp gl; M Jarvis con.
CONNACHT: F Murphy; T Nathan, F Carr, K Matthews, E Griffin; M Nikora, G Duffy; B Wilkinson, D Murphy, J Hagan; M Swift, B Upton; M McCarthy, J O’Connor, J Muldoon.
Replacements: D Fanning for Carr (68), R Loughney for F. Murphy (66), D Rogers for Wilkinson (66), B Fa’amausili for Hagan (52), E Taylor for Upton (62), A Browne for Muldoon (64).
OSPREYS: G Owen; K Phillips, S Parker, A Beck, R Fussell; M Morgan, R Webb; D Jones, M Davies, C Mitchell; C McInerney, I Evans; J Tipuric, M Holah, J Collins (capt).
Replacements: B Davies for Owen (57), M Jarvis for Morgan (72), J Nutbrown for Webb (57), J Goode for McInerney (41).
Referee: Peter Allan (SRU).