Rugby/ Leinster 20 Ulster 12:The key to the turnaround was perhaps in the press box, although only because that's where David Knox watched the game.
The Leinster assistant coach had detected his team were playing into the hands of Ulster's blitz defence and as coach Michael Cheika admitted afterwards, it was Knox's call to play back inside in the second period, dragging Ulster's backs in or turning them around to create more space off recycles. So the decisive tries followed.
It took Leinster a long time to win this match but you always sensed they had the winning of it. It helped too that they stopped spilling the ball, and with their minor adjustment, simply by dint of taking Ulster through the phases, clearing the ball out quickly with some excellent low rucking, they created three well- worked tries.
Helped by more impact off their bench, Leinster played with more ambition, creativity, accuracy and width and, having created several other try-scoring opportunities, could have secured a bonus point.
Ulster were tidy and efficient in building up an insufficient 12-5 interval lead with the benefit of the crossfield wind, but retreated into their shells in seeking to protect their lead, made too many mistakes and hardly created a try-scoring opening themselves.
They still lead the Magners Celtic League but Leinster's win revives not only their league hopes but also those of Ospreys and Llanelli, and perhaps even those of Cardiff, Edinburgh and Munster.
Ulster had the better scrum but they have rarely had such difficulties at lineout time. Given the wind, that Leinster won the better ball was a tribute to Bernard Jackman, who also had a big game around the park, and Malcolm O'Kelly's athleticism. Ulster didn't help themselves by opting too often to go long - desperately hazardous in a capricious wind.
Their cause wasn't helped by the cruel loss of David Humphreys five minutes into his last visit to a ground he has decorated memorably for over a decade.
Paddy Wallace injected pace and elusiveness into the Ulster outhalf role, landed three penalties from three when the wind was at its trickiest, and landed a drop-goal from the pocket with the last play of the first half.
Leinster are becoming a little paranoid about referees, and on the latest evidence are probably justified in feeling they are still suffering for previous run-ins with officials. Here, a 13-5 penalty count against them took the tally from their all-Irish festive doubleheader to 30-12.
Brian O'Driscoll felt Leinster were unfairly treated by George Clancy in the first half especially - at the end of which the penalty count was 10-3.
But Leinster did concede some inane penalties, notably for Wallace's opening three-pointer when Ronnie McCormack flapped the ball away from Isaac Boss when loitering yards offside on the fringes of a ruck.
Nor could there be any quibble with Denis Hickie's yellow card for killing ruck ball.
Critically, just before Wallace's drop goal, Hickie had scored his 27th league try off Shane Horgan's cut-out pass to justify his earlier quick tap under the sticks and atone for Simon Keogh's dropping the ball over the line when hit hard by Andrew Trimble.
A knock-on by Neil Best, hacked and chased upfield by O'Kelly, set the tone for the second period, O'Kelly then charging down Wallace's kick for a fired-up O'Driscoll to make an astonishing pick-up and Jonathan Sexton to make it 12-8.
So well did Sexton play generally, in defence, in taking on the opposition and in his kicking, that Cheika kept the youngster on longer than he intended. But the match changed when the darling of the Leinster faithful, Felipe Contepomi, appeared.
The key moment in the 14-man attack through eight phases that culminated in some big yardage by Stephen Keogh - the most improved forward in Irish rugby this season - was an excellent clear-out by Will Green, leading to a try for Owen Finegan.
Contepomi's wonderful sleight of hand, when suspending the ball in mid-air for Hickie to make a fingertip transfer to Kieran Lewis, was the spark for more quick ball, Jackman moving the ball on for Jamie Heaslip to score his third try of the season and seal a sixth game in a row without defeat against Ulster.
Leinster have their critics but they delivered in style here.
SCORING SEQUENCE: 22 mins: Wallace pen 0-3; 23: Wallace pen 0-6; 37: Wallace pen 0-9; 40(+1): Hickie try 5-9; 40(+4): Wallace drop goal 5-12 (half-time 5-12); 46: Sexton pen 8-12; 66: Finegan try, Contepomi con 15-12; 77: Heaslip try 20-12.
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: R Corrigan for McCormack (27 mins), O Finegan for Hogan (51 mins), F Contepomi for Sexton (63 mins), K Lewis for Kearney (73 mins), G Easterby for Whitaker (75 mins), H Vermaas for Jackman (80 mins). Sinbinned: Hickie (58 mins).
ULSTER: M Bartholomeusz; T Bowe, K Maggs, P Steinmetz, A Trimble; D Humphreys, I Boss; B Young, R Best, S Best (capt); J Harrison, M McCullough; N Best, K Dawson, R Wilson. Replacements: Wallace for Humphreys (5 mins), J Fitzpatrick for Young (66 mins), N McMillan for Dawson (69 mins), P McKenzie for Maggs (72 mins), K Campbell for Boss (77 mins), P Shields for R Best, T Barker for Harrison (both 80 mins).
Referee: George Clancy(IRFU).
