Three second half penalties from Felipe Contepomi earned Leinster a 9-8 Celtic League win over a battling Ulster outfit at Donnybrook.
Leinster (0) 9:
Pens: Contepomi 3.
Ulster (8) 8:
Ulster seemed on course for a surprise win when they led 8-0 at half-time with Tyrone Howe's 40th minute try adding to an early Adam Larkin penalty.
Two third quarter Contepomi penalties cut Ulster's lead to two points.
Ulster looked set to hang on but Contepomi's 79th minute penalty won the day for the home side.
Ulster's early pressure earned a third minute penalty which fly-half Adam Larkin struck between the posts.
However, Leinster soon took control but despite dominating play for the next half-hour they were unable to claim any scores.
The dreadful weather conditions didn't help with the home side thwarted by handling errors near the Ulster line on several occasions.
In addition, the visitors produced some fantastic last-ditch tackling with the superb Ulster forward Matt McCullough produced a standard which he somehow managed to keep up for the rest of the contest.
Ulster centre Paul Steinmetz produced a superb intervention in the 28th minute after Aidan McCullen's break had set up a glorious chance for Leinster.
Leinster introduced Brian O'Driscoll as a replacement before half-time which meant that he linked up in midfield with his Ireland colleague Gordon D'Arcy.
Tyrone Howe (left) scored Ulster's try in the first half
However, Ulster finally managed to break out of their own half as half-time neared.
A Tyrone Howe break produced a glorious chance in the 35th minute but the Ulster wing held on instead of finding Bryn Cunningham or Tommy Bowe and was soon swallowed up by an O'Driscoll tackle.
However, Howe atoned in first half injury when he intercepted D'Arcy's ambitious pass, kicked ahead and then produced some neat soccer skills before notching the touchdown.
Larkin missed the conversion but Ulster still must have been content with their 8-0 lead after having soaked up so much Leinster pressure.
Tempers flared after half-time and both O'Driscoll and Howe were sinbinned after indulging in some mild fisticuffs.
A Contepomi penalty cut Ulster's lead to five points and on the hour, the Argentine star added another three points to leave the visitors hanging on to their lead.
Leinster coach Declan Kidney introduced Ireland stars Shane Byrne, Malcolm O'Kelly, Eric Miller and Denis Hickie in the closing stages.
The introduction of the Leinster heavyweights kept the pressure on Ulster and Contepomi missed a chance to put the home side ahead when he just wide with a penalty eight minutes from time.
However in the final minute, Ulster replacement Rowan Frost needlessly killed the ball in front of his own posts to concede a penalty and Contepomi made no mistake to ensure a narrow Leinster win.
Leinster: Contepomi, Horgan, D'Arcy, Quinlan, Lewis, Holwell, O'Meara; , Corrigan (cpt), Blaney, Nebbett, Gissing, Cullen, McCullen, Ronan, Costello. Replacements: E Byrne, S Byrne, O'Kelly, Miller, O'Riordan, O'Driscoll, Hickie.
Ulster: Cunningham, Bowe, Steinmetz, Maggs, Howe, Larkin, Campbell; S Best; R Best, Moore, Longwell, McCullough, Feather (cpt), N Best, Wilson.
Replacements: Brady, McCormack, Frost, Mustchin, Doak, Wallace, Bell.