Cardiff Blues ended Leinster's seven-match unbeaten run with a close 11-3 Magners League victory at Cardiff City stadium on Saturday.
Full-back Dan Fish scored the only try of the game as Cardiff Blues completed a long-awaited victory over Leinster to move to second in the table.
It was the Blues' first win over the Irish province in eight attempts, ending a winless run stretching back to 2007, and maintains their quest for a home semi-final in the end of season play-offs.
Blues dominated territory and possession in a tense first half but only had a Ceri Sweeney penalty to show for their efforts.
A number of opportunities went begging as the Blues continually pressed forward, No.8 Xavier Rush going closest to scoring only to lose control of the ball with the line at his mercy.
On 30 minutes, though, the pressure finally told and quick hands from veteran flanker Martyn Williams gave Fish just enough time and space to squeeze over in the right-hand corner.
Sweeney was unable to land the touchline conversion and Leinster, led by lock Leo Cullen on his 150th appearance for the side, pulled the score back to 8-3 after Isa Nacewa was successful with his third attempt at goal.
Defences remained on top in the second-half with both sides putting in some big hits and it was left until the 75th minute before Dai Young's men finally sealed their 10th league win of the season.
Having missed with another attempt minutes earlier, Sweeney coolly stepped up to kick the penalty that killed off Leinster's resistance and also denied them a losing bonus point.
For Cardiff Blues:
Pens: Sweeney 2
Cardiff Blues: 15 Dan Fish, 14 Richard Mustoe, 13 Gavin Evans, 12 Dafydd Hewitt, 11 Tom James, 10 Ceri Sweeney, 9 Tom Slater, 8 Xavier Rush, 7 Martyn Williams, 6 Andries Pretorius, 5 Paul Tito (c), 4 Deiniol Jones, 3 Fau Filise, 2 Gareth Williams, 1 John Yapp.
Replacements: 16 Rhys Williams, 17 Sam Hobbs, 18 Scott Andrews, 19 Ben White, 20 Ma'ama Molitika, 21 Rhys Downes, 22 Dan Parks, 23 James Loxton.
Leinster: 15 Isa Nacewa, 14 Andrew Conway, 13 Eoin O'Malley, 12 Eamonn Sheridan, 11 Niall Morris, 10 Ian McKinley, 9 Isaac Boss, 8 Rhys Ruddock, 7 Dominic Ryan, 6 Kevin McLaughlin, 5 Devin Toner, 4 Leo Cullen (capt), 3 Clint Newland, 2 Richardt Strauss, 1 Heinke van der Merwe.
Replacements: 16 Jason Harris-Wright, 17 Jack McGrath, 18 Stan Wright, 19 Nathan Hines, 20 Stephen Keogh, 21 Eoin Reddan, 22 Ian Madigan, 23 Michael Keating.
Referee: Carlo Damasco (Italy)