A late penalty goal secured a win for the Irish province in a result that looked unlikely at the break, with the home side leading 26-14 after an explosion of brilliance which saw them score four tries and a earn their bonus point in the opening half.
The great tries by the home side in the opening 40 minutes rocked the Irish team, who then saw two players yellow-carded in the opening part of the second half. This, however, may have bolstered the visitors on the way to a famous win, although the will and belief to win are DNA samples of any Leinster player.
The hosts may have out-scored the visitors in the first half, but opening stanza belonged to Leinster, who had snap in their passing game from early on. That led to an early try to debutant prop Vakhtang Abdaladze, as the Georgian raced in from 30 meters out, following an inside pass that gave him space to run.
Two minutes in and seven down already did not deter the Emirates Lions though, who in the next 30 minutes played some of the best rugby the competition has seen.
First, Edwill van der Merwe sliced through the Leinster defence to score the opening try. Jaco Kriel won a turnover 40 meters out and the Johannesburgers' kicked to the corner. From the resulting lineout a smart backline move saw the left wing stepping in and out of the Leinster defence to dot down 13 minutes in.
The conversion went wide, but the home side grabbed the lead in spectacular fashion in the 25th minute when flyhalf Gianni Lombard scored after some sublime individual play.
From a standard backline move, he saw some space behind the charging Leinster defence, put the ball past the charging defence with a stunning grubber and then won the foot race to the line, twice toeing the ball ahead, with the second bouncing into his hands.
Sanele Nohamba converted for a 12-7 lead.
Leinster almost scored from the restart, crossing the tryline only to be held up, but a minute later, Liam Turner jogged in after some good inter-passing by his teammates put him in space and saw him make a clear run to the line. Sam Prendergast converted to hand Leinster a two-point lead.
The effortless way the try was scored should have triggered the warning light for the home side and their reply was breathless.
First Marius Louw scored a beautiful try, with the crack in Leinster’s defence came from a Van der Merwe break, who then made a chicken-wing pass to Nohamba with the scrumhalf throwing a blind pass to Louw. And Nohamba kicked the conversion for a 19-14 lead.
Francke Horn then scored after being put into space 40 meters out following a flat pass by Louw and his run down the touch line left a number of Leinster defenders clutching at straws. The No 8 dotted down for a brilliant score and Nohamba again converted for a 26-14 halftime lead.
Leinster were straight back into it from the start of the second half. They attacked well, with Prendergast prominent and the flyhalf’s efforts were rewarded when prop Michael Milne worked his way over from close range. With Prendergast's conversion, it was suddenly it was back to one score between the sides, although Nohamba kicked a penalty goal to ease the hosts' lead back to eight points.
Leinster scrumhalf Nick McCarthy was yellow carded when impeding close to his own tryline, but there was no reward for the home side as they lost the resulting lineout.
They tried again two minutes later when Leinster was pinged in their red zone, but the desperate Leinster defence kept them at bay - this time illegally as Chris Cosgrove’s lazy arm blocked a try-scoring pass, which earned the Emirates Lions a penalty try.
Prendergast slotted a penalty goal to cut the lead to 36-24 and still with a player down, they scored in the corner, with replacement back Rob Russell dotting down following a pinpoint cross kick from the impressive flyhalf.
Cosgrave made up for his earlier error at the right side of the field when a strong run resulted in a try that levelled scores with six minutes left to play, and Prendergast snatched the victory on the stroke of fulltime with a vital penalty goal for the narrow three-point victory.
Scorers:
Emirates Lions 36 (26) – Tries: Gianni Lombard, Marius Louw, Edwill van der Merwe, Francke Horn, Penalty Try. Conversions: Sanele Nohamba (3). Penalty goal: Nohamba.
Leinster 39 (14) – Tries: Vakhtang Abdaladze, Liam Turner, Michael Milne, Rob Russell, Chris Cosgrave. Conversions: Sam Prendergast (4). Penalty goals: Prendergast (2).