Leinster moved joint-second in the Magners League on Sunday after sealing a 26-16 win at the Dragons.
The match was tinged with controversy though as, with the game locked at 16-16, referee Andy Macpherson chose to award the Irish team the decision despite there being no definitive evidence that a try would have been scored.
Aided by 16 points from Jonathan Sexton, the result significantly boosts the away side's chances of making the end-of-season play-offs.
Having not won in Wales all season, Leinster came out determined to end that run and took an early three point advantage through Sexton.
Jason Tovey missed the chance to level matters soon after, before the Dragons scored the first try of the match just before the 20 minute mark.
After a huge hit by winger Aled Brew, the ball came to centre Adam Hughes who went all the way to the line, Tovey converting. Dragons extended that lead with a penalty but Leinster hit back when Isaac Boss touched down from close range, Sexton adding the extras.
However, Tovey restored the Dragons' advantage to make it 13-10 at half-time.
Not long into the second-half, Sexton levelled the scores with a penalty before winger Aled Brew was sin-binned for a trip on Isa Nacewa. Leinster's fly-half kicked the resultant three points but once again the Dragons hit back through another Tovey penalty.
On 55 minutes came the decisive moment in the match. Leinster were controversially awarded a penalty try much to the frustration of the Dragons crowd. And the score settled the away side's nerves with Sexton sealing the win with his fourth penalty.
Pen: Tovey 3
Tries: Boss, Penalty
Con: Sexton 2
Pen: Sexton 4
Dragons: 15 Martyn Thomas, 14 Will Harries, 13 Adam Hughes, 12 Tom Riley, 11 Aled Brew, 10 Jason Tovey, 9 Wayne Evans, 8 Toby Faletau, 7 Lewis Evans, 6 Joe Bearman, 5 Adam Jones, 4 Luke Charteris (capt), 3 Dan Way, 2 Lloyd Burns, 1 Phil Price.
Replacements: 16 Steve Jones, 17 Hugh Gustafson, 18 Ben Castle, 19 Adam Brown, 20 Gavin Thomas, 21 Matthew Pewtner, 22 Matthew Jones, 23 Jon Evans.
Leinster:15 Isa Nacewa, 14 Shane Horgan, 13 Eoin O'Malley, 12 Fergus McFadden, 11 Luke Fitzgerald, 10 Jonathan Sexton, 9 Isaac Boss, 8 Rhys Ruddock, 7 Dominic Ryan, 6 Kevin McLaughlin, 5 Devin Toner, 4 Leo Cullen (c), 3 Stan Wright, 2 Richardt Strauss, 1 Heinke van der Merwe
Replacements:16 Aaron Dundon, 17 Jack McGrath, 18 Simon Shawe, 19 Nathan Hines, 20 Jamie Heaslip, 21 Eoin Reddan, 22 Ian Madigan, 23 Dave Kearney.
Referee: Andy Macpherson (SRU)
Assistant Referees: David Bodilly, Simon Harris (WRU)
TMO: Tony Rowlands (WRU)