Wasps boss Dai Young believes Toulon lock Ali Williams should have been sent off before he scored the match-winning try in their quarter-final on Sunday.
Young was left frustrated after Williams escaped a "blatant yellow card" for tugging back Wasps centre Elliot Daly shortly before William Helu's second try which closed the gap to within seven points of Toulon with six minutes left in the game.
And to add insult to injury for the Premiership side, the former All Blacks second-row rounded off a flowing move by the European champions which secured them a 32-18 victory and a place in the semi-finals.
"There are three people who didn't see it – the referee and the two touch judges," Young told reporters.
"I don't want it to sound like sour grapes because they have probably had a bit too much for us on the day.
"But in saying that we ended up scoring three-and-a-half minutes later.
"So if we'd had a penalty try then and the yellow card, it would probably have allowed us to really mount a real challenge. It certainly would have made it interesting.
"It's frustrating because if you look at their first try, their lineout in the build-up was nowhere near straight.
"Little things go against you but when you've won the European cup twice you tend to get the 50-50s.
"We were hugely frustrated by that, hugely frustrated by the decision and them still having 15 players on the field when it was a blatant yellow card and a blatant sin-bin."