Leinster defended the summit of the Magners League by coming from behind to secure a gritty 24-17 victory over the Cardiff Blues at RDS in Dublin on Saturday, with three second-half penalties from Felipe Contepomi stealing back the lead.
But it was Leinster fullback Luke Fitzgerald who sealed the deal by grabbing a last-gasp try as the Irish province completed the double over the Blues for the first time.
Crowning a gritty comeback from the hosts, Fitzgerald chipped past his opposite number Ben Blair in the 75th-minute and got his left hand to the ball before it bobbled over the end line for the all-important score.
Having worked Maama Molitika and Nick Macleod over for tries inside the opening 11 minutes, Cardiff looked set to gain revenge for their 30-19 defeat to the Irish side in November.
But willed into action by 14-point fly-half Felipe Contepomi, Leinster stubbornly swung the tie in their favour.
Cardiff owned the ball for the opening four minutes, picking and driving their way into the Leinster 22 before flanker Molitika showed good co-ordination to touch down one-handed from close range.
Ben Blair added the conversion and the Blues produced some scintillating interplay for their second try.
Big Jamie Roberts made the initial thrust forward, Robin Sowden Taylor carried the ball on and found Jason Spice, who teed up his half-back partner Macleod for an angled run past Stephen Keogh and a smart finish to the left of the posts.
Blair again added the extras for 14-0 and Leinster were taking their time to settle - Contepomi knocked a Chris Whitaker pass on and centre Michael Berne lost sight of the ball as he chased an up-and-under.
They did find some joy by bringing the fit-again Shane Horgan in off his wing. The Irishmen gained some much-needed momentum and a 20th-minute ruck infringement from Xavier Rush allowed Contepomi to boot Leinster's first points, albeit after a dust-up between the Argentinian and Jason Spice.
With the Blues wavering slightly, Keith Gleeson and Ollie Le Roux, playing his first game for Leinster as a hooker, began to throw their weight around and after a long series of phases close to the visitors' try line, a Horgan pass put Berne stepping past Spice and over in the left corner.
Contepomi brilliantly converted that 32nd-minute try to close the gap to four points but Blair kicked the second of two penalty opportunities, just before the interval, to see the Blues turn around with a 17-10 advantage.
With their maul becoming an effective weapon, Leinster's pack grew in stature and Contepomi kicked the home side closer with a 47th-minute penalty.
The Blues were losing their way despite some fine kicks to touch from Blair and Tom James.
They lost Molitika to the sin-bin for persistent infringing at the ruck and Contepomi landed the resulting penalty for 17-16.
With Scott Morgan penalised at a maul just past the hour mark, the Pumas star then fired Leinster in front for the first time.
Cardiff clawed their way back into the Leinster half and won a lengthy penalty chance for Blair which he just missed to the right.
Macleod was also off target with a quick drop goal attempt and Fitzgerald's opportunistic five-pointer was enough to seal Leinster's sixth successive league win.
Tries: Berne, Fitzgerald
Pens: Contepomi 4
For Cardiff Blues:
Tries: Molitika, Macleod
Cons: Blair 2
Leinster: 15 Luke Fitzgerald, 14 Shane Horgan, 13 Christian Warner, 12 Michael Berne, 11 Gary Brown, 10 Felipe Contepomi, 9 Chris Whitaker, 8 Stephen Keogh, 7 Keith Gleeson, 6 Cameron Jowitt, 5 Leo Cullen (c), 4 Trevor Hogan, 3 Stan Wright, 2 Ollie le Roux, 1 Cian Healy.
Replacements: 16 Brian Blaney, 17 Stephen Knoop, 18 Devin Toner, 19 Kevin McLaughlin, 20 Chris Keane, 21 Eoin O'Malley, 22 Felix Jones.
Cardiff Blues: 15 Ben Blair, 14 Jamie Roberts, 13 Jamie Robinson, 12 Gareth Thomas, 11 Tom James, 10 Nick Macleod, 9 Jason Spice, 8 Xavier Rush (c), 7 Robin Sowden Taylor, 6 Maama Molitika, 5 Paul Tito, 4 Scott Morgan, 3 Tauf'au Filise, 2 Gareth Williams, 1 John Yapp.
Replacements: 16 Gary Powell, 17 T Rhys Thomas, 18 Ben White, 19 Mark Lewis, 20 Richie Rees, 21 Rhys Jones, 22 Tal Selley.
Referee: Peter Allan (Scotland)
Touch judges: Simon McDowell (Ireland), Ger English (Ireland)
Television match official: Dudley Phillips (Ireland)