Leinster coach Michael Cheika was left to rue a lifeless second-half show from his talented side following yesterday's 35-13 Heineken Cup quarter-final defeat away to Wasps.
"We are bitterly disappointed. We lost a really good opportunity," he said.
"We put ourselves in a really good position at the break and let it go. We gave everything but we didn't play to our ability in the second half.
"The impact that we had in the first half didn't come out in the second half.
"We knew they would run direct at us because they are very strong support runners and when you let them go through at the first point of contact you open the door. That caused errors.
"They came out firing with 14 men and took it to us. They deserved to get the points they scored at that time."
Will Green, Leinster's former Wasps prop forward, added: "It was just that 10-minute spell after half-time that changed the game.
"That was the winning factor — Lawrence was off the field and they scored 14 points. It was very frustrating.
"It's the end of our Heineken road this year and it makes us more determined to get it right next year."
Wasps director of rugby Ian McGeechan praised his side's combination of youth and experience.
The Guinness Premiership team twice overcame being reduced to 14 men to triumph in front of a 10,000 capacity crowd at Adams Park.
The two all-important tries were scored by young prospects James Haskell, a second-half replacement at flanker, and full-back Danny Cipriani.
But McGeechan paid tribute to his old hands Lawrence Dallaglio, Simon Shaw and outhalf Alex King, who re-emerged for the second half with 10 stitches in a head wound.
McGeechan said: "Sometimes you put things in a bottle called experience and you never know how much is in there. Fellows like Lawrence just know this environment.
"We tried to balance the experience with youth and put some of our young players into this cauldron.
"There is a balance between that experience and youth and it's always good to know you are playing alongside players who've been in every major tournament in the world, at both international and club level."
Wasps scored three of their tries when first Dallaglio and then centre Dominic Waldouck were in the sin-bin, and McGeechan said: "We played well both times with a man down.
"It sometimes focuses the mind for the players on the field. The pack were very good keeping the ball at that time and we defended superbly.
"We're delighted, particularly coming on as strong as we did in the second half. Leinster caused us a few problems in the first half and the way we responded was excellent."
Former England skipper Dallaglio agreed with McGeechan's assessment.
He said: "The two sin-binnings really galvanised the guys. We have to be really pleased with that performance because of the quality of the side we were up against.
"Most people predicted an away win and it really irritated me and my friends in the dressing room. We came in at half-time and said they were there for the taking."
Wasps' inconsistency has seen them struggling to secure a place in the Premiership championship play-offs and Dallaglio added: "We have, hopefully, seven games left this season and we want to pick them off one by one.
"We have to focus on getting back into the top four and be in two finals at the end of the season."