Keith Gleeson is tackled by Kevin Maggs at Lansdowne Road
Leinster (5) 20
Tries: Hickie, Finegan, Heaslip
Ulster (12) 12
Pen: Wallace (3)
Drop goal: Wallace
Leinster scored three tries in a 20-12 win over Magners League leaders Ulster to move to within three points of their Irish provincial rivals in the table.
Ulster led 12-5 at half-time with Paddy Wallace kicking three penalties and a drop goal to a try by Denis Hickie.
After the break Jonathan Sexton kicked a penalty and then Owen Finegan and Jamie Heaslip added touchdowns.
Replacement Felipe Contepomi converted Finegan's try in the final match to be played at the old Lansdowne Road.
Ulster suffered an early setback when David Humphreys retired hurt with an elbow injury after five minutes with his place being taken by Paddy Wallace.
Wallace made an immediate impact, knocking over penalties in the 22nd and 32nd minutes as his side enjoyed the advantage of a strong wind in the first period.
The fly-half's third penalty came off the post before dropping over to make it 9-0 after 37 minutes.
Stephen Keogh dropped the ball before he could touch it down after accepting Brian O'Driscoll's pass but Hickie raced over the line from Shane Horgan's pass in the first minute of added time.
Jonathan Sexton's attempted conversion hit the upright.
Wallace kicked a sublime drop goal in the closing seconds of the half to give his side a seven-point advantage at the break.
Sexton reduced the arrears with a 46th minute penalty but was well off target with his next effort from long range.
Rob Kearney was wide with an audacious drop goal attempt as Leinster enjoyed the majority of the possession.
Hickie was yellow carded in the 57th minute for deliberately killing the ball as Ulster threatened to score a try and Wallace was off target with the resulting kick for the posts.
Leinster's pressure paid off when Finegan drove over for a try on 64 minutes and Contepomi followed up with the conversion.
Heaslip completed a fine attacking move to score in the corner on 77 minutes and although Contepomi was unable to add the extra two points, the win was secure for Leinster in front of a crowd of 48,000.
Ulster coach Mark McCall:
"It was fantastic to have 20,000 Ulster fans here today and they kept cheering us at every stage of the match so all credit to them.
"It's been a tough month for us. We've struggled since we lost away to London Irish in the Heineken Cup and we've lost a bit of belief since them, even though we have dragged out a couple of wins.
"Again, we didn't play as well as we can today but I can't fault the effort and application of the players."
Man-of-the-match Stephen Keogh:
"I don't know how I got man-of-the-match because I dropped the ball when I was over the Ulster line in the first half.
"Our rucking improved a lot from Wednesday's game (against Munster) and we turned over a bit of ball.
"And when you have guys in the backs like Brian O'Driscoll, Denis Hickie and Shane Horgan, they can create something out of nothing."
Leinster: R Kearney, S Horgan, B O'Driscoll (capt), G D'Arcy, D Hickie, J Sexton, C Whitaker, R McCormack, B Jackman, W Green, T Hogan, M O'Kelly, S Keogh, K Gleeson, J Heaslip Replacements: Lewis for Kearney (73), Contepomi for Sexton (63), Easterby for Whitaker (74), Corrigan for McCormack (29), Vermaas for Jackman (80), Finegan for Hogan (51).
Not Used: Jowitt.
Ulster: M Bartholomeusz, T Bowe, P Steinmetz, K Maggs, A Trimble, D Humphreys, I Boss, B Young, R Best, S Best (capt), J Harrison, M McCullough, N Best, K Dawson, R Wilson. Replacements: McKenzie. for Maggs (72), Wallace for Humphreys (6), Campbell for Boss (77), Fitzpatrick for B. Young (66), Shields for R. Best (80), McMillan for Dawson (68).
Not Used: Barker.
Referee: G Clancy (Ireland).