Connacht (9) 15
Pens: Nikora 5
Ospreys (6) 16
Try: Nutbrown Con: Jarvis Pens: Morgan 2 Drop goal: Morgan
Matthew Morgan scored nine points on his Magners League debut
A late converted try saw the Ospreys snatch a one-point victory over Connacht at the Sportsground, Galway.
Connacht raced into the lead thanks to three Miah Nikora penalties but Matthew Morgan replied with three penalties to leave the score 9-6 at half-time.
A drop goal by debutant Morgan brought Ospreys level but two penalties by Nikora moved Connacht six points clear.
Replacement Jamie Nutbrown scored the 78th-minute try, with Matthew Jarvis adding the crucial conversion.
Nikora landed his first penalty after just three minutes and followed that up with successful kicks in the seventh and 18th minutes as the Irish province took control.
The New Zealander's second attempt was a cracking effort from the standside and his third came after a powerful scrum.
Teenager Morgan was on-target with his penalties on 21 and 36 minutes, having previously slipped while trying to open his side's account.
The Welsh side also had a near miss when Ashley Beck knocked on in sight of the try-line.
Good hands from Dermot Murphy and captain John Muldoon looked to have sent Fionn Carr over for the game's opening try but referee Peter Allan ruled that he had been held up in the corner.
Connacht had Bernie Upton yellow-carded six minutes into the second half for throwing a punch and a snap Morgan drop goal levelled the scores after a period of Ospreys dominance.
Connacht looked well placed to secure the win with those two further penalties by Nikora in the 71st and 73rd minutes.
Nutbrown crossed the line from close range two minutes from time after a defensive lapse.
Jarvis, another replacement, converted from in front of the posts.
The defending champions, despite being second best for most of the game, hung on to take the points.
Connacht engineered a last-gasp penalty for Nikora, but he missed from a difficult position.
Connacht: F Murphy; M Nikora, F Carr, K Matthews, E Griffin; T Nathan, G Duffy; B Wilkinson, D Murphy, J Hagan, M Swift, B Upton, M McCarthy, J O'Connor, J Muldoon.
Replacements: R Loughney for F Murphy (66), B Faamausili for Hagan (52), D Rogers for Wilkinson (66), A Browne for Muldoon (64), E Taylor for Upton (62), D Fanning for Carr (68).
Not used: C Willis, I Keatley
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: J Goode for McInerney (41), J Nutbrown for Webb (57), M Jarvis for Morgan (72), B Davies for Owen (57).
Not used: S Baldwin, J Rees, C Griffiths, J King
Referee: Peter Allan (SRU)