The Ospreys held off the challenge of the Dragons at the New Stadium in a scrappy but fierce Welsh derby.
Ospreys: (15) 15:
Tries: Brew, Penalty try.
Cons: M Jones.
Pen: M Jones.
Dragons: (6) 9:
Pens: Warlow 3.
Home wing Aled Brew was the only player to cross the whitewash, but referee Nigel Whitehouse also awarded the Ospreys a penalty try.
That decision, plus three sin-binnings, made sure that it was the officials who took centre stage.
The Dragons had few clear-cut scoring chances and had to settle for three penalties from fly-half Craig Warlow.
The Ospreys will not be proud of the style of their win, but after their horror show in Munster at the weekend they will be delighted with the character and the result.
After an early Warlow penalty, the Ospreys hit back with a try from Brew in the corner.
Jason Spice sent quick ball from the base of a ruck down the backs and skipper for the night Leigh Davies showed great vision to float a long pass into his wing's arms.
Matthew Jones missed the conversion, but made no mistake with a penalty just after the quarter-hour mark to stretch the home side's slim lead to 8-3.
Referee Whitehouse had been warning both sides not to deliberately kill the ball and he finally lost patience with the Dragons, sending flanker Jamie Ringer to the sin-bin.
The Newport-Gwent side made light of being a man down, though, and worked a position for Warlow to kick his second penalty.
But then full-back Kevin Morgan went offside to slow Ospreys' possession and became the second Dragons player to earn a yellow card.
Briefly down to 13 men, the Dragons defence did well to hold Stefan Terblanche up as the Ospreys full-back crossed the try line.
The Ospreys opted to keep the pressure on and the Dragons pack conceded a string of penalties as they tried to stop a succession of scrums.
Mr Whitehouse's limited patience ran out again and the referee awarded a penalty try, easily converted by Jones for a 15-6 lead at half-time.
Dragons fans could be forgiven for feeling a little aggrieved that decisions had largely gone against them in the first half.
But Mr Whitehouse soon showed his even-handed nature by sin-binning Ospreys prop Duncan Jones for hanging on after making a tackle.
Warlow kicked the resulting penalty and suddenly the pressure was back on the Ospreys.
The homes side rode out the 10-minute danger period by letting the forwards punch holes around the fringes and the game remained delicately poised entering the final quarter.
Gareth Wyatt nearly produced a winner, but the Dragons wing's chip and chase down the touchline was cut off by the excellent Davies.
With that went the visitors' last real chance to snatch a win, although they at least claimed a bonus point for losing by seven points or less.
Ospreys centre Leigh Davies:
"With just two or three days' rest after a huge game in Munster, the boys showed character and spirit.
"It was a physical encounter out there, Gwent just threw everything at us, and we're delighted with that win.
"It's great to be back and the boys either side of me - Sonny (Parker) and Matthew (Jones) - have really helped."
Ospreys: S Terblanche; R Mustoe, S Parker, L Davies (capt), A Brew; M Jones, J Spice; D Jones, H Bennett, A Jones, B Cockbain, I Evans, J Thomas, S Tandy, A Lloyd.
Replacements: James for A Jones (70), Newman for Cockbain (49), Wyn Jones for Lloyd (78).
Not Used: B Williams, Wells, Connor, A Bishop.
Dragons: Morgan; Wyatt, Luscombe, Bryant, Breeze; Warlow, Baber; Black, Crawford, R Thomas, Gough, Charteris, Ringer, Forster (capt), Bryan.
Replacements: Tuipulotu for Breeze (72), Robinson for Crawford (56).
Not Used: Maddocks, Hall, Oakley, Hinton, A Thomas.
Referee: Nigel Whitehouse (WRFU).