Ospreys scraped a win over Connacht with a penalty deep in injury time thanks to a controversial decision by Scottish referee Rob Dickson.
Ospreys: (3) 18:
Pens: Jones, Connor 5.
Connacht: (9) 17:
Pens: Warwick 4.
The Irish side were penalised for taking too long over a 22 drop-out and Shaun Connor happily slotted the kick.
It was harsh on Connacht, who seemed to have grabbed a winning lead thanks to Keith Matthews' late try.
But Connor, a half-time substitute, drove the Ospreys forward and kicked superbly to finish with 15 points.
Connacht had the best of a poor first half, at least managing to occasionally threaten the try line.
But the Irish side's best opportunity was wasted by left wing Matt Mostyn, who ignored the spare man outside him and was tackled.
The Ospreys' saviour was full-back Adrian Cashmore, the former All Black making his debut for the Welsh side.
Cashmore - who has signed on a two-year contract - might be forgiven for wondering what he has let himself in for, as the Ospreys produced a first-half display that sometimes just managed to reach lacklustre.
Connacht's other chance fell to Conor O'Loughlin, as the scrum-half broke brilliantly from the base of a scrum in his own 22 and rocketed upfield.
O'Loughlin had the confidence to try and take on Lions wing Shane Williams - making his season's domestic bow - on the outside, but did not have the pace.
It was left to the kickers to get the scoreboard moving.
Ospreys fly-half Matthew Jones adding his side's solitary first-half points with a penalty in the second minute, while opposite number Paul Warwick struck three times.
Jones paid the penalty for his poor decision-making and was replaced at half-time by Connor.
Connor at last got the Ospreys ticking over and for the first time Connacht founf themselves under pressure.
Referee Rob Dickson penalised Connacht for taking too long
The Irish defence just managed to hold out when Ospreys number eight Andy Lloyd charged through a gap, but started to ship penalties at an alarming rate.
Warwick did strike his fourth of the night for the visitors, but Connor converted all four of his chance to give the Ospreys a 15-12 lead.
The last of those came after Connacht lock Chris Short was sent to the sin bin for stamping on Lloyd, lying prone on the wrong side but nowhere near the ball.
Yet despite being a man light Connacht at last found their way to the try line.
Darren Yapp found a gap in midfield, as Leigh Davies got his defensive alignment horribly wrong, and Matthew raced through for an unconverted try.
Then came a moment of controversy from referee Dickson that turned the match on its head.
Connor missed a long-range kick but when Connacht dawdled over taking the 22 drop-out, Mr Dickson penalised the incredulous Irish and gave Connor a simple chance to kick the winning penalty.
Ospreys coach Lyn Jones:
"We're right at the bottom of our game at the moment and we've got a lot of work to do.
"We scraped a win over Connacht, but I don't know who was the best team.
"If we kick as badly and as openly against Stade Francais next week they will cut us apart."
Ospreys: Cashmore; Karauna, A. Bishop, Davies, S. Williams; M. Jones, Spice; D. Jones, B. Williams, A. Jones, Cockbain, Evans, Thomas, Tandy, Lloyd.
Replacements: Connor for M. Jones (40), Bennett for B. Williams (57), Newman for Cockbain (56), Beech for Tandy (47). Not Used: James, Rees, Vaughton.
Connacht: M Mostyn; C McPhillips, J Hearty, K Matthews, D Yapp; P Warwick, C O'Loughlin; R Hogan, J Merrigan, S Knoop; C Short, A Farley (c); M Swift, B O'Connor, J Muldoon.
Replacements: Riordan for Mostyn (72), Robinson for Hearty (52), Keane for O'Loughlin (65), Loughney for Hogan (67), Fogerty for Merrigan (55), Rigney for Swift (35), Lacey for O'Connor ().
Referee: Rob Dickson (Scotland)