"So delighted to come out on the right side of the result", Leinster coach Stuart Lancaster said.
Racing were dealt a blow just before kick-off when All Blacks legend Dan Carter withdrew from the bench with injury.
But Racing's heroic defence in the face of Leinster's increasing dominance of possession held firm and when Sexton opted to run a kickable penalty, Camille Chat was in place to pluck the ball from Leavy's arms at a ruck to win a penalty and the Parisians cleared their lines. "We have to do things slightly differently in Leinster where we produced guys from within mainly".
"We were very close".
However, Racing will have to do without their first-choice out-half-scrum-half combination, as well as their two-time World Cup winning back-up.
"I haven't played against Pat Lambie much".
A relieved and delighted Sexton, who has been with the club for all of its triumphs in Europe's premier competition, said: "We did it the hard way".
It looked as though the French side might have been about to edge the boys in blue when Teddi Iribaren scored his fourth penalty of the day with just ten minutes to go. "It's for them really".
"Off the bench he's still a threat for them".
"He still a world-class player who will be keen to make an impact when he does come on".
"But what we want to do is not only to worry them, but to beat them".
Racing replacement Remi Tales missed the chance to slot an equalising drop goal with the last kick of the game as Leinster won their fourth European title with a 15-12 win over the Parisians in Bilbao, Spain.