Toulon burned birghtly in the second period to deny Leo Cullen's side a share of the points
Leo Cullen will take a lot of positives from his side's narrow defeat at the Aviva Stadium this afternoon, but their much improved performance couldn't prevent defeat to a Toulon side that were there for the taking.
A nine-point halftime lead was a fair reflection of how he first half had panned out; quick hands, good rucking and some excellent kicking meant that any time Toulon ventured into the Leinster '22, the Irish province had the answer.
It was after the interval that Toulon showed their class and a rake of changes to the front row meant that Leinster struggled in vain to keep the three-time French champions at bay midway through the second half.
Johnny Sexton gave the home side an early lead from the boot, his confident kicking settled the nerves and set the tone for the first 40 minutes. This was a Leinster side who weren't going to be pushed around.
Adventurous was one of the main adjectives that could be used to describe their attack as they varied between quick off-loads, kicks to touch and the kick and chase which set the Kearney brothers up for a good first half.
Their oply try of the game then unsurprisingly came in the first half, after some good work in the scrum from Jamie Heaslip helped a rolling maul to charge toward the Toulon line and the referee was given no choice but to award the penalty try.
Ben Te'o celebrates as Leinster win a penalty try Image: ©INPHO/Ryan Byrne
With 20 minutes played, Leinster led 10-0 and this had all the makings of an upset or resurgence, whichever side of the fence you looked at it from.
The try was a wake-up call for Toulon, who finally came into their own and fashioned a score just minutes later.
In all, they could have run out comfortable runners had they not thrown away a rather inexcusable seven points away from kicks over the course of the evening.
Toulon pulled the deficit back to 10-5 when increased pressure inside the Leinster '22 finally opened up a gap on the left hand side and Juan Smith crossed.
It was 13-5 just shortly after, Sexton again proved infallable from the dead ball and extended their lead, something Eric Escande failed to do after the visitors try.
The gap was nine points at the break, Sexton completing his final of three kicks of the day to put Leinster comfortably ahead.
In the second half, it was Toulon's territorial dominance that proved the difference.
Drew Mitchell missed a catch that would have given him a free run to cross the whitewash and if not for Sean Cronin, Leinster would have been behind earlier, but his try saving tackle did little to stem the Red tide of French players.
Toulon maintained the pressure and finally were awarded what felt an inevitable.
Cian Healy came on as a replacement and was battered Levan Chilachava in the scrum, giving referee Wayne Barnes no choice but to head under the sticks for the penalty try.
Replacement fullback Tom Taylor tacked on the extra points from the conversion and Anthony Etrillard rounded off the scoring to put the French side four points clear.
With seconds to go, Leinster needed to run the length of the pitch, with only a try enough to give them victory. But some poor handling resulted in a knock-on and it was appearent, if it hadn't been before, that the side just ran out of gas.
Leinster Jack McGrath and Mike McCarthy with Drew Mitchell of Toulon. Image: ©INPHO/Dan Sheridan
It was a much improved performance from the home side, but in the end they ran out of steam and an effective second half performance in the physical sense saw Toulon push by a resurgent Leinster.