Paddy Jackson's boot made the difference for Ulster tonight at Kingspan Stadium, dispatching a last-gasp penalty to see off a combative Dragons side and nudge the province above the Scarlets and Connacht to the top of the Guinness PRO12.
The visitors, who had two men sin-binned and put four Ulstermen out of commission in the course of a bruising encounter, led on the scoresheet for a good 70 minutes but were eventually squeezed out by a Sean Reidy score, penalty try and seven points from the boots of Jackson and Ian Humphreys.
With Rory Best, Jared Payne and Andrew Trimble the only three Ulster representatives retained in Joe Schmidt's Six Nations squad for the test against Wales, Rob Herring started at captain and hooker while both Jackson and Stuart McCloskey - fancied by many to feature in green on Sunday - took a place on the bench.
Talismanic scrum-half Ruan Pienaar, recovered from a recent illness which kept him out of the matches against Oyonnax and Benetton Treviso, returned to the starting XV as one of four changes made by Director of Rugby Les Kiss.
Jacob Stockdale made his full debut on the left wing after an impressive cameo appearance last Saturday at the Stadio Monigo, while Pete Browne started in the second row in place of the rested Franco van der Merwe, and Robbie Diack was preferred to Clive Ross at openside.
Elsewhere, Louis Ludik continued at full-back, with Craig Gilroy occupying the other wide berth, Darren Cave and Stuart Olding operating in the centre, and Humphreys at out-half with Jackson on the bench.
The front three went unchanged with Callum Black and Ricky Lutton propping Herring, while Alan O'Connor continued his good run at lock, and Diack and Reidy flanked Roger Wilson in the back row.
Dragons belied their lowly Pro12 standing - 10th going into the tie with only Zebre and Treviso beneath them - with a strong start, capped by Angus O'Brien's fifth minute penalty. In their turn when Ulster got going from the restart they were electric, with Olding and Stockdale contributing powerful line breaks.
However it was Dragons wing Ashton Hewitt who lit up Kingspan Stadium on 16 minutes, his virtuoso run from his own half evading five Ulster tacklers before Adam Hughes slid over from Carl Meyer's flagwards kick.
No sooner had O'Brien converted than Ulster pounded downfield from the restart, a rolling maul then five-metre scrum paving the way for Olding then Humphreys to almost breach the whitewash within seconds of each other.
Resolute Dragons defending kept the two backs at bay, but there was no stopping Reidy in the very next attack as the flanker brushed aside three tackles to run in at the corner for his third try in as many successive outings.
Humphreys converted and was soon celebrating what he thought was the self-same achievement as he intercepted a loose pass and sprinted to the line, only for referee Nigel Owens to call play back to half-way for an Ulster knock-on which had conceded possession seconds before, without the Dragons' advantage being served.
Half-Time Score Ulster 7 Dragons 10
Jackson and McCloskey entered the fray for the second half in place of Humphreys, victim of a knock just after his disallowed try, and Ludik; soon to be joined by Nick Williams as Diack took a heavy impact.
Dragons were next on the scoresheet, however, as Meyer touched down on 46 minutes after good work from his forwards, but a high tackle on Pienaar from Ben White got Ulster the close-range lineout, and another well-bossed driving maul - with Reidy once again at the helm - forced the penalty try as Matthew Screech collapsed the melee metres from the line.
Jackson's conversion and the sin-binning of Screech heralded the definitive turning of the tide in Ulster's favour - their cause helped further still by the yellow-carding of White for his second high tackle in five minutes, this time putting Browne out of the game.
The breakthrough looked to have come on 65 minutes, Wilson grounding right in the corner off Jackson's pass for a try initially validated by Mr Owens, then scrubbed off for an earlier knock-on after much deliberation from the TMO.
A nasty blow to the head for Olding spelled an early end to the match for the luckless centre, and with Ulster still trailing by a solitary point as the game entered its final 10 minutes, Kingspan looked on is disbelief as a long-range Jackson penalty landed on the Dragons' crossbar and rebounded back into Welsh hands.
The out-half got another chance from closer range with two minutes to go, and this time applied just the right power to dip his kick over the bar and seal the victory.
Next up for Ulster are reigning champions Glasgow Warriors, visitors to Kingspan on Friday 12 February.
Full-Time Score Ulster 17 Dragons 15
Ulster (15-9) Louis Ludik; Craig Gilroy, Darren Cave, Stuart Olding, Jacob Stockdale; Ian Humphreys, Ruan Pienaar
(1-8) Callum Black, Rob Herring (c), Ricky Lutton, Alan O'Connor, Pete Browne, Robbie Diack, Sean Reidy, Roger Wilson
Replacements (16-23) John Andrew, Kyle McCall, Bronson Ross, Clive Ross, Nick Williams, Paul Marshall, Paddy Jackson, Rory Scholes
Newport Gwent Dragons (15 - 9) Carl Meyer; Ashton Hewitt, Adam Hughes, Adam Warren, Hallam Amos; Angus O'Brien, Charlie Davies
(1 - 8) Phil Price, Elliot Dee, Brok Harris, Matthew Screech, Rynard Landman (c), Ben White, Nic Cudd, Ed Jackson
Replacements (16 - 23) Rhys Buckley, Boris Stankovich, Shaun Knight, Cory Hill, James Benjamin, Sarel Pretorius, Geraint Rhys Jones, Nick Scott