Leinster bounced back from successive European losses to beat Ulster 8-3 in a low-scoring PRO12 clash at the RDS on Friday.
The 2014 champions were staring down the barrel of three consecutive defeats following the first two rounds of the Champions Cup, but the Dubliners did just enough to prevail here with a controlled forward performance.
The Leinster pack was immense, particularly back-rower Rhys Ruddock who looked particularly dynamic with ball in hand.
The hosts' superior ball control was enough to earn them a slender half-time advantage without playing especially well.
The second-half was scoreless as Ulster chased the game, but the whites were kept out by a combination of outstanding defence and Sexton's tactical kicking. In truth, this scrappy, dour match never really came to life but for a beleaguered Leinster, the win was all that mattered.
Leinster grabbed the first points of the evening when Sexton angled over a five minute penalty, a reward for their early pressure.
Ulster responded well, though, and immediately set up camp in the hosts' red zone. Their efforts earned Jackson a gilt edged chance to restore parity on nine minutes, but incredibly Ulster's fly-half missed right in front of the posts.
Jackson made no mistake with a more difficult kick on thirteen minutes, however, to tie the game up at 3-3.
Both sides demonstrated plenty of ambition early on as they kept the ball in hand and played with tempo. Leinster managed a purple patch in the middle of the half, but struggled to make it count.
The hosts dominated possession when Andrew Trimble bundled the ball into touch five metres out on 20 minutes. From the ensuing lineout, Leinster went through phase after phase in the Ulster 22 but to no avail.
Thereafter they were awarded a series of five metre scrums, and the hosts' pack seemed to have the edge over their northern counterparts.
When Jamie Heaslip picked and drove at the base on 26 minutes, the Dubliners pummelled the Ulster line and seemed to have scored when Devin Toner got over the whitewash. The grounding was inconclusive, though, and the TMO correctly ruled out the try.
The home pack was beginning to get a bit of momentum by this point, and the inevitable happened on 37 minutes. They set up a powerful maul from a five metre lineout and a ferocious drive helped hooker Cronin barge over for his try. Sexton missed the conversion to leave it 8-3 to Leinster. As the teams traipsed off for the interval, Leinster had the edge but were struggling for fluidity.
The hosts nearly had the perfect start to the second-half when Ruddock laid waste to Ulster's defence before getting the ball away to Ben Te'o, but the centre knocked on with the line at his mercy.
The game became much more fractured in the next few minutes as the swirling wind made tactical kicking a lottery. While the conditions weren't conducive to either side, the wind slightly favoured the hosts and the Dubliners were able to keep their opponents pinned back through Sexton's kicking.
For their part, the visitors had plenty of possession in this phase of the game but had no real penetration, the home side's defence always looking pretty comfortable.
Leinster weren't doing anything that spectacular, but they didn't need to as the Ulster backs struggled to create much with ball in hand.
With the clock ticking down, the Belfast men pounded away at the Leinster defence with a tenacious resolve, but the rear guard was simply outstanding in the last ten minutes.
Time and again, the northerners hammered away only to be chopped down by a succession of Leinster tacklers. It wasn't a perfect victory by any means, but Leinster will just be glad to return to winning ways.
Leinster: 15 Rob Kearney, 14 Zane Kirchner, 13 Ben Te'o, 12 Ian Madigan, 11 Luke Fitzgerald, 10 Johnny Sexton, 9 Luke McGrath, 8 Jamie Heaslip (c), 7 Josh van der Flier, 6 Rhys Ruddock, 5 Mike McCarthy, 4 Devin Toner, 3 Tadhg Furlong, 2 Sean Cronin, 1 Jack McGrath.
Replacements: 16 James Tracy, 17 Peter Dooley, 18 Martin Moore, 19 Ross Molony, 20 Dominic Ryan, 21 Eoin Reddan, 22 Noel Reid, 23 Garry Ringrose.
Ulster: 15 Peter Nelson, 14 Andrew Trimble, 13 Darren Cave, 12 Stuart McCloskey, 11 Craig Gilroy, 10 Paddy Jackson, 9 Ruan Pienaar, 8 Nick Williams, 7 Sean Reidy, 6 Robbie Diack, 5 Dan Tuohy, 4 Iain Henderson, 3 Wiehahn Herbst, 2 Rory Best (c), 1 Kyle McCall.
Replacements: 16 Rob Herring, 17 Andrew Warwick, 18 Ricky Lutton, 19 Roger Wilson, 20 Chris Henry, 21 Paul Marshall, 22 Ian Humphreys, 23 Louis Ludik.
Referee: John Lacey (IRFU)
Assistant Referees: Andy Brace, Olly Hodges (both IRFU)
TMO: Dermot Moloney (IRFU)
by Rory McGimpsey