Jamie Heaslip's 200th Leinster appearance got off to the dream start when Ben Te'o crossed for the game's opening try, but Iain Henderson answered for the Ulstermen and Ruan Pienaar's boot edged them 13-10 up at the break.

And after an error-strewn start to the second-half, two penalties in quick succession from Pienaar proved decisive after Rob Kearney saw yellow, and Gilroy charged over with seven minutes remaining to make sure of victory.

With the Kingspan rocking, Leinster started like a side who knew how much was at stake, Jimmy Gopperth making a superb break inside the first minute which led to an early offside penalty for the boys in blue, with Henderson the man penalised.

And despite initially turning down the shot at goal, Leinster went three points up after some superb defending from Ulster led to another penalty in front of the posts - Gopperth kicking the game's opening points with ease.

And Leinster continued their superb start when Te'o charged over on eight minutes, latching onto Gopperth's pass and breaking a couple of weak tackles to score before the fly-half added the extras.

It looked as though the game could go away from Ulster very quickly when Pienaar then missed from the tee after 11 minutes - Devin Toner penalised for not rolling away - but that seemed to spark the hosts back into life as they came back into the contest with style.

Paddy Jackson was the architect with a wonderful initial break, and Henderson cut the line and charged over to bring Ulster roaring back on 13 minutes.

Pienaar made no mistake this time with the conversion, and when Leinster were caught offside on their own 22 just three minutes later the South African levelled the scores at 10-10.

The momentum had well and truly shifted, and things got even worse for Leinster when Sean O'Brien saw yellow for a dangerous tackle.

The wet weather brought mistakes from both sides, and Ulster were not able to add to their total even with the extra man - Pienaar missing again from distance when Heaslip was penalised for playing the scrum-half.

But the hosts did edge in front for the first time in the game on the stroke of half-time, Jared Payne with a strong carry before Gopperth was caught offside and Pienaar gave Ulster the half-time advantage.

The second-half began with both sides looking cagey, the ball moving from end to end with neither team wanting to make a mistake.

Gilroy thought he'd scored after collecting Jackson's inch-perfect grubber in the corner, but the TMO showed Kearney had done enough in the tackle to force his foot into touch.

As the game entered the final quarter the Ulstermen still held their slender lead, and finally edged themselves further in front thanks largely to Louis Ludik.

The full-back surged through before finding Tommy Bowe who took the hosts to the five-metre line, and when Kearney was sin-binned for slapping the ball down Pienaar made them pay with the penalty.

And Pienaar turned the screw two minutes later, taking Ulster nine points ahead with a kick from halfway, before Gilroy put the game to bed on 73 minutes.

Brilliant build-up play by Ulster's forwards allowed Jackson to put the ball back inside to the GUINNESS PRO12's top try-scorer to condemn Leinster to their eighth defeat of the season.

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