Leinster's idea of taking the Magners League title on Friday was firmly extinguished by Edinburgh, who took the points at Murrayfield with a 15-13 win.
The Dubliners were seeking a bonus-point triumph to tie up the championship but they suffered a repeat of their Heineken Cup defeat.
Edinburgh had gone into battle on the back of hammerings at the hands of Glasgow and Cardiff which wrecked their own title dreams.
However, they rediscovered their form to force Leinster to keep their champagne on ice.
But they had luck on their side as Felipe Contepomi's last-gasp penalty hit the post.
Both teams made a predictably jittery start with basic handling mistakes dominating the early exchanges.
Leinster launched the first telling raid and Argentinian Contepomi broke the deadlock with a confidently-struck penalty in the seventh minute.
Edinburgh's reply was powerful and potent as they surged in front, thanks to a fine touchdown by fit-again hooker Ross Ford.
The Scotland star was in the right place at the right time out wide to finish off a slick handling move.
And Phil Godman slotted the tricky conversion, giving the Gunners a potentially solid platform.
Gunners carved out further opportunities, but it was the Irish side who got the scoreboard clicking again as Contepomi doubled his penalty tally.
However, it took Edinburgh only two minutes to restore their advantage through the boot of Godman.
There was a setback for the Scots in stoppage time, however, as skipper Ally Hogg was yellow-carded for a professional foul.
Leinster stepped up the pace going into the final half hour but still the Gunners markers were holding firm.
And having soaked up the pressure they delivered the killer blow when flanker Dave Callam galloped through for the second try.
Luke Fitzgerald revived Leinster's prospects with a pack-drive touchdown, goaled by Contepomi.
Then came high drama deep in stoppage time as the Gunners were penalised for handling on the deck, leaving Contepomi with a simple strike which crashed back off the woodwork.
Tries: Ford, Callam
Pens: Contempomi 2
Edinburgh: 15 Hugo Southwell, 14 Simon Webster, 13 Ben Cairns, 12 Nick De Luca, 11 John Houston, 10 Phil Godman, 9 Greig Laidlaw, 8 David Callam, 7 Alan MacDonald, 6 Allister Hogg (c), 5 Ben Gissing, 4 Matt Mustchin, 3 Gavin Kerr, 2 Ross Ford, 1 Augusto Allori.
Replacements: 16 Andrew Kelly, 17 Geoff Cross, 18 Craig Hamilton, 19 Scott Newlands, 20 Ben Meyer, 21 David Blair, 22 Calum MacRae.
Leinster: 15 Girvan Dempsey, 14 Luke Fitzgerald, 13 Brian O'Driscoll, 12 Felipe Contepomi, 11 Rob Kearney, 10 Jonathan Sexton, 9 Chris Whitaker, 8 Jamie Heaslip, 7 Shane Jennings, 6 Stephen Keogh, 5 Trevor Hogan, 4 Leo Cullen (c), 3 Stan Wright, 2 Bernard Jackman, 1 Ollie le Roux.
Replacements: (from) Brian Blaney, Stephen Knoop, Malcolm O'Kelly, Cameron Jowitt, Keith Gleeson, Chris Keane, Christian Warner, Michael Berne, Gary Brown.
Referee: Nigel Owens (Wales)