Harlequins head coach Danny Wilson says the "damage was done" in the first half as his side were beaten 38-26 by Toulouse in their debut Investec Champions Cup semi-final.

Quins trailed 31-12 at the break before reducing the deficit to five points in the second half and threatening an upset against the five-time winners at Stadium de Toulouse.

Jack Walker's yellow card stunted their progress minutes before Toulouse finally broke Quins' resistance to score their first points of the second half as Juan Cruz Mallia claimed their sixth try of the match.

"We got done at the breakdown and they counter-rucked and turned us over," Wilson told BBC Radio 5 Sports Extra.

"When you go through a lot of phases like we do to break teams down, you are in trouble when your breakdown is not really good.

"The best teams dont just turn you over, they score off the turnover and that really hurt us.

"Maybe the yellow card was a moment when the momentum went away from us. I can understand the decision by the letter of the law but it was a key moment and they scored immediately to get a cushion."

Toulouse scored five first-half tries and were cruising until Quins hit back through Cadan Murley and Tyrone Green.

Wilson says he is "proud" of his players for mounting a comeback.

"We looked like Quins again [in the second half], sorted our breakdown problems out, got some speed of ball and every time we got into their 22 we looked like we would score," he added.

"Its the first time the club has ever been in a European semi-final so it was always going to be about learnings.

"Most of the learnings are positive ones. It shows we are on the right course. Im proud of what weve done but a part of you will always look at it and think about what we could have done."