Leinster survived a stirring second-half comeback from Ulster to win a thrilling Irish derby in Belfast and move above their rivals in the United Rugby Championship standings.
The visitors dominated the first half and led 15-0 through James Culhane and Jimmy O'Brien tries.
Robbie Henshaw and Sam Prendergast secured Leinster's bonus point and extended the advantage to 29-0 after 55 minutes to set Leo Cullen's side on course for a dominant win.
But Ulster came roaring back with three tries from the Ward brothers - one from Bryn and two from Zac - to rock Leinster, who were reduced to 14 men when Max Deegan's yellow card for a high hit on Werner Kok was upgraded to a 20-minute red.
Despite that surge of momentum, Ulster were unable to find two late scores as Leinster held on for a big late-season win.
The result means Leinster replace Ulster in third place in the table with three rounds of regular-season games remaining before the play-offs.
Despite making 12 changes from last week's Champions Cup quarter-final win over Sale, Leinster dominated the first half, refusing to allow their hosts attacking momentum as they built a comfortable lead.
Early injuries to Angus Bell and James Hume set the tone for Ulster in the first half before Culhane crossed to cap a sustained spell of Leinster pressure. Prendergast converted and then stretched the away side's lead with a penalty.
Ulster were unable to capitalise on the few opportunities they created in the first half, with Jude Postlethwaite's momentum-shifting jackal penalty failing to yield a first try for the home side.
Ulster's woes deepened when Leinster won a penalty advantage off a scrum and quickly worked the ball to Hugo Keenan, who played in O'Brien to cross in the corner and ensure a 15-point gap at the break.
