There was just one point between the sides as the final five minutes approached and victory was far from guaranteed for a home side that looked undercooked.
The Kiwi scrum half’s snipe and dive, and Ross Byrne’s conversion, wrapped up a hard-fought victory — but Leinster know a lot of improvement will be needed ahead of the visit of Munster next weekend.
Edinburgh didn’t look like a team willing to be overawed by their more illustrious hosts in the opening exchanges, with Richard Cockerill’s men roaring out of the blocks, dominating possession and territory, as Leinster barely touched the ball in first ten minutes.
James Johnstone, the Edinburgh centre, and Cornell Du Preez, the No 8, punched holes through Leinster’s brittle defence, and the hosts looked happy to give up only two penalties in that time.
Jason Tovey slotted both home to give the Scots an early six-point lead, making hay as Leinster struggled to find their feet.
Dougie Fife was lucky not to be sent to the bin when the airborne Dave Kearney was toppled over by his opposite number, who failed to leave the ground. He had a duty of care to the Leinster player, but referee Ian Davies dismissed Sexton’s vocal appeal.
No matter, Leinster got over their sense of injustice from the very next play, with Seán Cronin barreling toward the tryline from the resulting lineout. Jordi Murphy picked up from the back of the ruck and shoved home for his first try since May 2016.
Referee Davies was back in the thick of things after the restart, when a mass brawl broke out with Scott Fardy, Leinster’s Australian lock, the guilty party.
On review, the TMO spotted Darryl Marfo, the Edinburgh prop, playfully tapped Fardy on the head, a gesture that was greeted with a more fulsome swing in return.
Nonetheless, Davies was happy to see the pair engage in a firm handshake, and hostilities resumed with both sides at full strength.
Leinster were eager to up their tempo now, with Sexton’s quick tap penalty taking them deep into enemy territory. The hosts reset and Sexton flung inside toward Furlong, but Tovey intercepted and ran home from inside his own half.
This was not quite what the home crowd expected, nor was seeing Fardy soaring on the touchline to gather a Sexton chip inches from the tryline, after a typical Cronin break. The support celebrated a try but replays showed a wonderful intervention by Dougie Fife to deny the Australian.
With one minute remaining in the first half, Sexton backed his lineout when a five yard scrum penalty arrived, and his bravery was rewarded.
Furlong and O’Loughlin softened up the opposition, before the ball was whipped wide to Carbery, whose dancing feet took him beyond the flailing Tovey.
Leinster began the second half in a different gear to the first, with a stylish Tadhg Furlong offload almost earning a try. Murphy supported at pace and fed McGrath, but the rampaging loosehead was taken down by Grant Gilchrist with the line in sight.
There was just one point between the sides on 50 minutes, but Jamie Ritchie’s yellow card for a late tackle on Luke McGrath’s standing foot as he kicked clear, threatened to turn the game on its head.
Alas, the home team were as subdued as their support, and too many passes were forced or went astray, allowing Ritchie to return to an unchanged scoreboard.
Fife had the small traveling support on their feet when he touched down after good play by Anton Bresler and Jorn Hardie, but the TMO spotted a block by Du Preez on Fardy in the buildup.
Leinster’s bench was emptied by now, but they were still just one point clear when Sexton left the park after a tetchy 69 minutes.
It looked like a bit of magic would be required to separate the teams, but instead it was a mistake. Blair Kinghorn’s attempted clearance put his defence under needless pressure, and when Max Deegan rose highest to steal possession, a sharp snipe from Gibson-Park finally gave Leinster some wriggle room.
J Carbery; F McFadden, R O’Loughlin, N Reid (rep: Larmour, 59), D Kearney; J Sexton (c) (rep: R Byrne, 69), L McGrath (rep: Gibson-Park, 65); J McGrath (rep: B Byrne 59), S Cronin (rep: E Byrne, 59), T Furlong (rep: Porter, 59); D Toner, S Fardy; R Ruddock, J Murphy (rep: Molony, 75), S O’Brien (rep: Deegan, 59).
G Bryce; D Fife, J Johnstone, P Burleigh, T Brown (rep: Kinghorn, 59); J Tovey, S Hidalgo-Clyne (rep: Fowles, 54); D Marfo, S McInally (rep: Cochrane, 31-38, 59-), S Berghan (rep: Bryce, 51); F McKenzie (c) (rep: Bresler, 46), G Gilchrist; J Ritchie, H Watson (rep: Hardie, 61 [rep: Freuan, 75)), C du Preez.
Ian Davies (WRU)