Leinster struggled to reinvigorate their Magners League title defence at a bitterly cold RDS but did enough in the second half to see off the Dragons. Though they ran riot on the last occasion the two teams met in Dublin, sealing their title with a 41-8 in May, this time it was an altogether different game.
The Dragons stuck doggedly to their task and even led for a large chunk of the first half. But despite some inspired play, which included a 40-metre break from flanker Joe Bearman, the visitors fell away in the final half-hour, leaking tries to Bernard Jackman and Rocky Elsom.
Replacement fly-half David Holwell, who has rejoined Leinster on a temporary contract, chipped in with a late penalty, as did centre Fergus McFadden who did his prospects no end of good with an impressive display.
And although Leinster managed to recover from an early 13-3 deficit, the night was somewhat soured by a shoulder injury to Brian O'Driscoll. With 10 players currently out injured, Michael Cheika can ill-afford to lose a player of O'Driscoll's calibre.
In wintry conditions, the Dragons settled into their stride and they deservedly moved 6-0 ahead thanks to two James Arlidge penalties. They were aggressive in the tackle and gave Leinster little room to manoeuvre, with Wayne Evans, Tom Willis and Bearman all eager for work.
With Jonathan Sexton receiving medical attention, McFadden booted the hosts' first points after 19 minutes, but the Dragons pulled 10 points clear when second row Hoani MacDonald grabbed an intercept try, swooping on a loose pass from Sexton to gallop over close to the posts, just after Arlidge had missed a penalty.
Leinster responded almost immediately with flanker Sean O'Brien coming in on a great angle into the Dragons' 22 and he handed off Arlidge to touch down with great aplomb. Sexton converted and while the Dragons lost MacDonald to the sin-bin for his hauling down of Devin Toner at a lineout, their lead still stood at 13-10 at the break.
With better continuity and a solid platform up front, Leinster began to turn the screw in the third quarter. Sexton levelled matters with a well-struck penalty and after repeated darts at the Dragons line, hooker Jackman gave Leinster some relief by scoring on the hour mark.
The try went unconverted as Sexton's kick bounced off the left-hand post and had Arlidge bisected the uprights soon after at the other end, the pressure would have mounted on Leinster.
As it was, the hosts had enough class on show to see out a win which moves them up to fourth in the table.
Holwell kicked the second of his two penalty attempts, McFadden also landed a penalty and then, in injury time, after a fantastic raid forward from Girvan Dempsey, Holwell showed great hands to send Elsom tearing over at the right corner to add some gloss.
Leinster: Dempsey, Horgan, O'Driscoll, McFadden, S. Keogh, Sexton, Whitaker, Healy, Jackman, Wright, Toner, O'Kelly, Elsom, O'Brien, S. Keogh.
Replacements: Jowitt for S. Keogh (62), Holwell for Sexton (65), Keane for Whitaker (65), Hogan for Toner (67). Not Used: Blaney, van der Linde, Brown.
Newport-Gwent D'gons: Dolman, Wyatt, Sidey, Stcherbina, Fussell, Arlidge, W. Evans, Black, Willis, Robinson, MacDonald, Hall, Bearman, L. Evans, Webb.
Replacements: Connor for Arlidge (61), S. Jones for Willis (75), Corsi for Robinson (75), Lydiatt for Hall (27), Ringer for Webb (47). Not Used: Smith, R. Lewis.
Att: 16,000
Ref: Andy MacPherson (SRFU).