Rob Kearney predicts the manner of Leinster's Champions Cup final defeat to La Rochelle will hurt the province "for a long time".
The Blues fell to a 25-21 defeat in Marseille last Saturday, conceding a converted last-gap try to Les Maritimes when Leo Cullen's men had one hand on the trophy for a fifth time.
Instead, it was Ronan O'Gara's Top 14 underdogs who finished the stronger and claimed a deserved first crown at this level.
Former Leinster full-back Kearney, Ireland's most decorated player, reflected on the worst disappointments of his career as he analysed how the province will deal with this one.
"The two most devastating defeats in my career were, by a long shot, the Lions in 2009, and then when we played the All Blacks in the Aviva in 2013," he said.
"The one in South Africa...obviously you have to get back on the horse straight away.
"The game against the All Blacks stung for a long time and it took me weeks to get over.
"I don't remember a game for Leinster that hurt as much. I suppose Saracens in that Champions Cup final in 2019.
"But this one is going to hurt them for a long time, it really will."
Leinster had to quickly pick themselves back up, however, as they will face Glasgow Warriors at the RDS on Saturday (3.15pm) in the URC quarter-finals.
"It is great that they have the opportunity to still fight for a trophy," said the now-retired Kearney, who will be working for Premier Sports on quarter-final weekend.
"Of course, it's not the one that they or the club wanted but there's nothing worse than finishing a season on a final you've lost and you don't get an opportunity to play another game for a few months.
"The best thing for the whole group of players and the coaches is to get back on the horse straight away."
And Kearney believes that after losing the European decider, Cullen will deviate with his selection plan.
The Blues supremo, he feels, will turn to more of those who played last weekend to go again at the start of the URC play-offs than he had wanted to, rather than keep them fresh for the semi-final and final.
"Had they won the final at the weekend you'd be seeing a very different team I would suspect this weekend," said the Louthman.
"That's part of the job of the coaches - are there some players who have performed unbelievably well who now deserve their opportunity?
"Just because a player wants to get back on the horse and right the wrongs of the week before doesn't necessarily mean that they will get that opportunity again.
"That's part of being a coach and making sure you are keeping the morale in the group pretty strong still.
"I'd still expect a lot of guys to be involved this weekend who weren't involved in the final."
Rob Kearney will be part of the Premier Sports team bringing live coverage of all four URC quarter-finals this weekend.
Kearney joins Ross Harries, Stephen Ferris, John Barclay and Ryle Nugent for full build-up and live action of Leinster v Glasgow Warriors on Premier Sports 2 from 3pm.
Tune-in to every second of the drama live on Premier Sports - sign up at www.premiersports.com
Friday June 3 Ulster v Munster, Premier Sports 2 from 6.30pm (KO 7.35pm)
Sat June 4 Vodacom Bulls v Cell C Sharks, Premier Sports 2 from 12.15pm (KO 12.45)
Sat June 4 Leinster v Glasgow Warriors, Premier Sports 2 from 3pm (KO 3.15pm)
Sat June 4 DHL Stormers v Edinburgh, Premier Sports 2 from 5.30pm (KO 6pm)
