Leaders Leinster got the job done to go seven wins from seven in what was a scrappy interprovincial with both teams looking rusty after the break.
Tries from Luke McGrath, Jordan Larmour, Jimmy O’Brien and James Culhane ensured Leo Cullen’s side took maximum points from the game though the result was only secured late in the game after what had been a very nip and tuck affair at the Kingspan Stadium.
Ulster got off to the perfect start with a try from Ben Carson after just four minutes when a ball moved wide went through Werner Kok and James McNabney, the latter putting Carson away down the touchline to dot down out on the right wing.
Nathan Doak added a superb conversion and Ulster were up and running.
But a restart error gave Leinster an immediate route back and on penalty advantage, Luke McGrath skated through at the posts giving Ross Byrne a straightforward conversion to tie things up after just nine minutes.
Shortly afterwards play a high collision by Brian Deeny appeared to connect with Aidan Morgan’s head which led to an 11th minute yellow card for the Leinster lock.
Doak nailed the three points from the tee and Ulster were back in front.
Again, Leinster came back and off another Ulster scrum which was deemed to be in trouble Ross Byrne did the needful to tie things up again at 10-10.
Ulster were back in the red zone soon afterwards after a break from Doak but when Will Connors strayed offside under their sticks, the hosts opted for the corner with what was a regulation kick but coughed up a penalty from an illegal drive off their maul.
Still, Ulster did visit the scoreboard again winning a penalty near the posts following a series of pick and goes, this time Doak called for the tee and put the ball between the sticks to again put the home side in the lead on the half hour.
From there, no further scores were registered by either side as the opening half descended into a penalty fest against both teams though Ulster will have felt more disappointed at not pushing the scoreboard onwards to improve on their 13-10 lead.
The half was only three minutes old when Nick Timoney was shown yellow for a collision with Scott Penny.
Leinster went for the corner and moved the ball right only to be pinged for infringing on the Ulster line, this prompted the arrival of RG Snyman which coincided with a downpour to add further difficulty to an already messy enough encounter.
Leinster needed to make the extra man count and on 49 minutes when good work from Jimmy O’Brien nearly put Osborne in only for the ball to recycled and then moved right where Jordan Larmour sliced through.
Ross Byrne added the extras.
With Timoney back, Ulster struck found a way back. Camped in Leinster’s 22, Carson surged through for his second with Doak’s conversion of the 55th minute effort putting Ulster 20-17 ahead.
The pattern continued as four minutes later Leinster had the lead. This time a penalty was put to the corner and after a strong drive from Lee Barron, the ball was spun at pace, Larmour delivering for Jimmy O’Brien in the corner.
Ross Byrne was just wide with the conversion and Leinster led by just two points, but this was extended in the 72nd minute as James Culhane drove over from a lineout to claim the bonus point score for Leinster.
Ross Byrne missed from a difficult angle with the extras and despite a strong finish from the hosts, Leinster held firm, stealing a late lineout and clearing their lines to claim the five points.
S Moore; W Kok, B Carson, J Postlethwaite, M Lowry; A Morgan, N Doak; E O'Sullivan, J McCormick, S Wilson; A O'Connor (capt), K Treadwell; J McNabney, N Timoney, D McCann
: T Stewart for McCormick (53'), A Warwick for O’Sullivan (53'), C Barrett for Wilson (53'), H Sheridan for Treadwell (67'), Marcus Rea for Cooney (71'), J Cooney for Moxham (37'), J Humphreys for Morgan (65'), B Moxham for Kok (12').
J O'Brien; J Larmour, L Turner, C Tector, A Osborne; R Byrne, L McGrath; J Boyle, J McKee, R Slimani; D Mangan, B Deeny; M Deegan, W Connors, J Conan (capt)
: L Barron for McKee (45'), M Milne for Boyle (14-25' and 66'), R McGuire for Slimani (71'), RG Snyman for Deeny (45'), J Culhane for Deegan (36') and for Mangan (69'), F Gunne for McGrath (58'), H Byrne for Osborne (71'), S Penny for Connors (25'), Deegan for Culhane (h-t).
: E Cross (IRFU)