Ospreys (15) 22
Tries: Spratt, Tandy, Vaughton Cons: Biggar (2) Pen: Biggar
Connacht (3) 10
Try: Nathan Con: Dunne Pen: Keatley
Jonathan Spratt marked his return from injury with a fine try
A weakened Ospreys squad overcame Connacht but failed to claim the bonus point that would have put them clear in second place in the Magners League.
Jonathan Spratt got an early try, but Richard Hibbard limped off injured and Ian Keatley landed a Connacht penalty.
Steve Tandy crossed for a fine try on the stroke of half-time, Jon Vaughton adding a third with 20 minutes left.
But the Ospreys failed to push on, man-of-the-match John Muldoon outstanding for Connacht who got a Troy Nathan try.
The result leaves Connacht rooted to the bottom of the league, the Ospreys level with Leinster in second spot, three points behind leaders Munster.
The Ospreys side - weakened by injury and without 13 players on international duty - had their problems compounded when Wales hooker Hibbard limped off.
But the home side started strongly, Vaughton cutting the defence in the third minute before off-loading with a fine over-the-shoulder inside pass to Spratt.
The centre showed his recent injury has not affected his speed, having the pace to sprint home for a try converted by Dan Biggar.
The visitors came back strongly, Keatley missing a sixth-minute penalty after good build-up work from Gavin Duffy, while Fionn Carr, Keith Matthews and Niva Tau'auso all threatened.
An early injury to Richard Hibbard was a blow to the Ospreys
Keatley was helping to spark some stylish moves, and the fly-half got his side on the scoreboard with a 28th-minute penalty.
Biggar cancelled that out with a superb long-range penalty then, with the last move of the half, the Ospreys struck a killer blow.
Strong and patient build-up work took them to within 10 metres of the Irish line, ruck ball was delivered to Biggar, and the fly-half's long, looping miss-pass sent flanker Steve Tandy clear to the line on the wing.
Keatley missed a further penalty, before the Ospreys tried to turn the screw by introducing Marty Holah, Filo Tiatia and David Bishop from the bench.
Flanker Jonathan Thomas, released from the Wales squad to gain playing time after injury, went close as the Ospreys pressured the Connacht line.
We're pleased with the win with a young team out
Ospreys flanker Jonathan Thomas
Carr nearly intercepted another looped Biggar pass, but only succeeded in tipping it on to Vaughton who crossed in the corner, Biggar converting from the sidelines.
The Ospreys failed to go for the kill and the vital bonus-point try in a lacklustre closing.
It was left to Connacht to round off the scoring, Andrew Browne driving forward strongly and off-loading to Nathan who went over under the posts for a try with a drop-goal conversion from Andy Dunne.
Ospreys and Wales flanker Jonathan Thomas:
"Personally I'm just very delighted to get through the game, it's been a very difficult season with injury.
"As a player you just want to be on the pitch and it was great to be out there with the boys.
"When all the focus is on the Six Nations the Magners League can get forgotten, it's difficult, but we're pleased with the win with a young team out and we'll look forward to playing Leinster in a fortnight.
"It would be great for me to play a part next week [for Wales against France] but it's up to the coaches. I'll turn up to training [Monday] and take it from there."
Ospreys: Owen, K. Phillips, Parker, Spratt, Vaughton, Biggar, Nutbrown, James, Hibbard, Griffiths, Levi, Thomas, Tandy, Smith, Tiatia.
Replacements: Beck for Parker (78), D. Bishop for Spratt (59), Webb for Nutbrown (75), Shervington for Hibbard (24), Bevington for Griffiths (67), Holah for Tandy (59), Lloyd for Tiatia (59).
Connacht: Duffy, Carr, Ta'auso, Matthews, Bibo, Keatley, Murphy, Wilkinson, Cronin, Morris, Browne, Farley, J. Muldoon, Ofisa, Rigney.
Replacements: Nathan for Ta'auso (65), Dunne for Keatley (65), Campbell for Murphy (71), Loughney for Wilkinson (79), Flavin for Cronin (72), Gannon for Rigney (40). Not Used: Swift.
Ref: Peter Allan (SRFU).