THERE is a fact regarding Leinster's rise to the summit of European rugby which has largely gone unnoticed, and it is this: the province's only significant Heineken Cup defeat over the last four seasons occurred when Jonathan Sexton was not playing.
That was the semi-final in the Stade Municipal in Toulouse when Leinster produced one of their bravest performances of the professional era, but, with the set-piece under extreme pressure and Australian centre Shaun Berne filling in as makeshift out-half, they were unable to match the power of the hosts.
Since Felipe Contepomi's injury in the 2009 semi-final against Munster allowed Sexton to show what he can do at elite European level, he has been a central figure in Leinster's rise to prominence, playing crucial roles in the 2009 and 2011 triumphs and again in the progression to tomorrow's final against Ulster in Twickenham.
Ronan O'Gara's sustained excellence has complicated matters at international level and saw the Munster man win back the No 10 jersey during the World Cup, but Sexton used that experience to emerge stronger and the confidence that deserted him off the tee in New Zealand is now coursing through the 26-year-old.
The statistics back it up. At the World Cup, Sexton's place-kicking return was a disappointing 47pc, but in the Six Nations he slotted 22 from 25 kicks while his return for Leinster is hovering around the 90pc mark and scooped him the Pro12 Golden Boot Award last week.
Sexton turns 27 in July and is nearing the peak of his professional career, says legendary Leinster, Ireland and Lions out-half Ollie Campbell, who believes his own best rugby was played between 1979 and 1983 when he entered his late 20s.
"It is remarkable to think how far Jonathan has come since he came on for Felipe Contepomi in that semi-final against Munster and kicked that penalty," says Campbell.
"That was in 2009 and people might forget, but in January of that year, Jonathan played for St Mary's against Old Belvedere (Campbell's club) in an All-Ireland League match because he wasn't getting enough game time with Leinster.
"To go from that point to kicking that penalty, and then dropping that audacious goal in the final against Leicester, to where he is today, he has possibly developed more quickly than any other player in the country."
Campbell can relate to Sexton's international tussle for the No 10 jersey with a Munster rival from his own rivalry with Tony Ward in the late 1970s and early '80s.
He remains a huge admirer of O'Gara's and agrees with national coach Declan Kidney that Ireland are "blessed" to have two world-class out-halves at their disposal.
However, as a Leinster supporter, Campbell's is delighted with Sexton's development in a position where the province struggled through the late 1990s and into the 2000s.
"He is just a class act, with hardly any weaknesses, even by the highest standards," says Campbell.
"He really has all the skills, he can play the kicking game, he is a beautiful passer off either hand and also a fully paid-up member of the out-half tackling union. I know he struggled with his kicking at he World Cup, but that is in the past, he has a good style and I do not see it as a long-term issue at all.
"Another factor is that I think he has absolutely blossomed under (Leinster coach) Joe Schmidt. Jonathan is very fortunate to have Joe Schmidt as a coach and Schmidt is equally fortunate in having Jonathan as his out-half -- the timing of Joe coming in, in terms of the development of Jonathan's game was perfect.
"Since he's come back from the World Cup, he has played some magnificent rugby," adds Campbell. "I'm thinking about that dummy in the lead-up to Isa Nacewa's try (reminiscent of Campbell's dummies for Moss Finn's try against Wales in 1982) in the quarter-final against Cardiff and then the blind pass in the same game -- that was hell of a play.
"Who knows how much better he can get for Leinster and Ireland with the confidence he has got this season, particularly if Leinster win tomorrow and he has three Heineken Cup winners medals in his pocket."
If Sexton has developed rapidly in recent years, it has mirrored the giant strides taken by Leinster in a relatively short period of time and Campbell clearly recalls a time, not so long ago, when there was still a ramshackle element to the operation.
"It is remarkable how far Leinster have come. When Michael Cheika arrived first, Leinster were still togging out in portakabins in Old Belvedere, that is only six years ago.
"Now, they are at the forefront of Irish and European rugby and I think these are the glory days for Ireland in the Heineken Cup, with Ulster taking massive steps forward also. It is wonderful to think that after tomorrow, Ireland will have its sixth Heineken Cup trophy, the same as England and one more than the French."
However, for all Campbell's admiration of Leinster under Schmidt, he see's tomorrow's final as a incredibly tight affair and says Ulster are more than capable of spoiling Leinster's back-to-back aspirations.
"It will be a lot closer than most people think, I wouldn't underestimate Ulster for a second. Any team that can go to Thomond Park and beat Munster deserves the utmost respect.
"They have a match-winner in Ruan Pienaar as well. He is a remarkable player and has almost re-defined the role of the scrum-half. I would expect a tight game tomorrow. Out of 16 finals, only two have ended beyond one score."
As for Sexton, regardless of tomorrow's result, Campbell is convinced he will go on to become one of the great out-halves (a group that contains players of the calibre of Campbell, Ward, O'Gara and Jackie Kyle).
"I wouldn't put any limits on what Jonathan Sexton can achieve," is Campbell's simple summation.