Wasps came from 9-23 down to level the match but a late Yachvili penalty saw the French side take the win.
“We have to be honest and say that at one stage we were dead and buried,” Young said.
“I thought the players showed a lot of guts and determination to claw themselves back into it and with eight minutes to go it could have gone either way. If we had a little bit more fire-power we could have won it but I am not sure we would have deserved it. They threw away a lot of chances you have to say.”
Wasps ended the game with eight players aged 21 or under (Morris, Launchbury, Jones, Davies, Wade, Daly, Prydie, Wallace) and Young paid tribute to the effort of his young stars,.
“Look we were lucky to be in the game at times but I was very proud of the team especially the young guys. They gave everything and showed a lot of character. You look at Launchbury and Jones and their impact in the back-row and then players like Daly and Wade who have been outstanding and Jack Wallace did a great job today when he came in. Those players will be better for the experience. There is a disappointed dressing room in there but they should be proud of our run in this competition. We came up against some tough French sides and we gave a good account of ourselves. Today we lacked the fire-power of our opposition and Yachvili was outstanding but we can take the positives and move forwad.”