Dragons (12) 18
Tries: Penalty try, Thomas. Cons: Tovey. Pens: Arlidge 2.
Leinster (6) 9
Pens: McFadden 3.
Dragons prop Rhys Thomas tests the Leinster defence
The Dragons ended another disappointing Magners League campaign on a high note with a scrappy win over an under-strength Leinster side in Newport.
A penalty try and a fine score from full-back Martyn Thomas gave the home side a 12-6 lead at the interval.
Leinster's Fergus McFadden added to his two first-half penalties with a third successful kick after the break.
But James Arlidge sealed victory for the Dragons with two penalties at the end of desperately poor half of rugby.
With their thoughts focused on next Saturday's Heineken Cup final and nothing riding on this final league fixture of the season, the visitors lined up with an inexperienced side as their international stars enjoyed a weekend off.
But the youngsters were soon into their stride on a blustery evening in Newport, and the home side were forced into some frantic defending straight from the kick-off.
Leinster continued to dominate possession and territory for the next 20 minutes, but their only reward was a McFadden penalty after eight minutes.
Despite being forced on the back foot, the Dragons should have been ahead but Tovey wasted two relatively simple penalty kicks at goal.
They also enjoyed a numerical advantage for 10 minutes until the 27th minute as Leinster openside flanker Sean O'Brien was sent into the sin bin a persistent offending at the ruck.
But seconds after O'Brien returned to the field, the Dragons sprang into a superb counter-attack which brought a penalty try.
A chip ahead from Rhodri Gomer-Davies created the opening and McFadden was adjudged two have impeded Tovey as the Dragons fly-half chased after the ball to the Leinster try line.
McFadden was sent to the sin bin for the offence, while Tovey added the simple conversion from under the posts.
The unexpected shift in the balance of power swung even further five minutes later as Thomas finished off fine move across the backline as the Dragons stole ball from a Leinster line-out.
Tovey sliced his conversion attempt, and there was still enough time for McFadden to return to the field to land a second penalty to cut the Dragons' lead to 12-6 at the break.
The basic skills level dropped considerably in the early stages of the second half, but the home side began to stamp their authority on the game with long periods of possession.
It was Leinster who scored first, though, as McFadden confidently stroked over another penalty.
But his next effort was way off the mark as he miss-hit a long-range kick from the halfway line with 15 minutes left.
Replacement fly-half Arlidge restored the Dragons' six-point advantage with a penalty on 73 minutes and his second kick a minute from time put the result beyond doubt.
Dragons: Martyn Thomas; Gareth Wyatt, Rhodri Gomer-Davies, Phil Dollman, Richard Fussell; Jason Tovey, Wayne Evans; Adam Black, Tom Willis (capt), Rhys Thomas, Andrew Hall, Luke Charteris, Dan Lydiate, Lewis Evans, Craig Hill.
Replacements: Steve Jones, Nigel Hall, Huw Gustafson for Black (67), Grant Webb for Hill (67), Aled Brew for Gomer-Davies (75), James Arlidge for Tovey (60), Alex Walker for W. Evans (73).
Leinster: Girvan Dempsey; Simon Keogh, Fergus McFadden, Kyle Tonetti, Rob Kearney; Ian McKinley, Chris Keane; Ronan McCormack, John Fogarty, Stephen Knoop, Trevor Hogan, Devin Toner, Kevin McLaughlin, Sean O'Brien, Stephen Keogh (capt).
Replacements: Brian Blaney, Jamie Hagan for Knoop (77), Cameron Jowitt for S. Keogh (49), Paul Ryan, Paul O'Donohoe for Keane (49), Ian Madigan for R. Kearney (74), David Kearney for Tonetti (59).
Referee: Graham Knox (SRU).