Leinster defeated Irish rivals Ulster 13-9 in the Pro12 semi-final thanks to a second-half comeback at the RDS.
Ulster fly-half Paddy Jackson kicked over two penalties in an error-strewn first half to the give the visitors a 6-0 lead at the break.
Jackson added a third penalty before Jimmy Gopperth started the Leinster fightback with two penalties.
Ian Madigan burst through for the only try with eight minutes left and Leinster held on for the victory.
Ulster made a blistering start in Dublin but they failed to capitalise on their early dominance.
Ruan Pienaar missed a penalty before Jackson slotted between the posts after seven minutes to give the visitors a deserved lead.
Ulster were desperate for a try but they were frustrated by handling errors and a stiff Leinster defence.
Leinster began to show their attacking potential but they were also guilty of turnovers in a half littered with mistakes and infringements.
Gordon D'Arcy was sin-binned on 34 minutes when the Leinster centre clattered into Tommy Bowe after the wing cleared upfield.
Ulster pressed as the break approached and Jackson slipped over his second penalty in added time.
Leinster centre Brian O'Driscoll, who will retire after the Pro12 final, was forced off five minutes into the second half under concussion rules after banging his head in tackling Iain Henderson.
Jackson gave Ulster a cushion with a 52nd minute penalty but Gopperth fired over six minutes later to reduce the gap to six points.
Peinaar charged down down a clearance but Leinster wing Fergus McFadden won the race for the loose ball as it trickled over the try line.
Gopperth made it 9-6 in the 64th minute with his second penalty and Leinster again held up Ulster close to the line before Madigan delivered the killer blow.
The fly-half was fed by Gopperth's neat lay-off and he burst through three Ulster tackles before diving over.
Gopperth added the extras and the defending champions withstood intense pressure from Ulster in the closing minutes to secure a place in the decider against Glasgow Warriors.
And while O'Driscoll can look forward to another game, the defeat ends the career of retiring Ulster captain Johann Muller while team-mates John Afoa and Tom Court are leaving Ravenhill for new clubs.
Leinster: R. Kearney, McFadden, O'Driscoll, D'Arcy, D. Kearney, Gopperth, Reddan, Healy, Cronin, Moore, Toner, Roux, Ruddock, Jennings, J. Heaslip.
Replacements: Kirchner for McFadden (66), Madigan for O'Driscoll (50), Boss for D. Kearney (69), Dundon for Cronin (69), Cullen for Roux (53), O'Brien for Ruddock (56), J McGrath for Healy (67), Ross for Moore (56)
Sin Bin: D'Arcy (35)
Ulster: Gilroy, Bowe, Payne, Cave, Trimble, P. Jackson, Pienaar, Black, Best, R. Lutton, Muller, Henderson, Diack, Henry, Wilson.
Replacements: L. Marshall for Cave (56), McKinney for P. Jackson (56), Tuohy for Muller (58). Not Used: Herring, Warwick, Macklin, Doyle, P. Marshall.
Ref: Leighton Hodges (WRU).