And in a quite remarkable turnaround Leinster scored 27 unanswered points after the interval to win 33-22, Sexton scoring all but five of those points in an outstanding individual display.
And Sexton admitted that he drew on his 'nerdy' sports knowledge to fire up his troops and implore them to keep faith in the second half.
"We were shell-shocked and we needed leaders at half-time," he said.
"I said that comebacks happen in finals and used the example of Liverpool in the Champions League. I knew we could come back from the deficit."
"We knew we had it in us. We have played well in patches throughout the season and the second-half performance was immense.
"It felt it was gone when they got that third try, that everything we had done to get out of the pool and get to the final was down the drain.
"We regrouped. We had to believe and we took our chances. We have leaders who stood up in the second half. We did everything in the first half we said we weren't going to do.
"But when a team gets a score and gets the momentum going it is hard to stop. It was like a snowball effect."