Cardiff Blues director of rugby Phil Davies rued a missed opportunity for his side after they went down 22-14 at home to Toulon in the Heineken Cup.
The Welsh team also lost to Sale in their opener, meaning their European campaign already looks doomed after just two of the six matches in Pool Six.
Steffon Armitage's 63rd-minute try turned the game in Toulon's favour, Jonny Wilkinson kicking the visitors' other 17 points at Cardiff Arms Park.
"I feel a lot of pride and a lot of frustration, for 80 minutes we stuck in there and performed superbly well and gave ourselves a platform to potentially win the game but for a bit of inaccuracy and a bit more field position we could have beaten one of the strongest squad in Europe, and it would have been a huge plus for our group," said Davies.
"We had a couple of opportunities in the second half and gave away a couple of cheap penalties, but the quality of our game was there for all to see, it was a shame we did not have the accuracy to get over the line."
Toulon prop Gethin Jenkins, making his return to the club he left last summer, said the result was more impressive than the performance.
"We are disappointed with how we played, but glad to come here and get a win, two out of two in Europe puts us in a good position leading into the Sale games in December," said Jenkins.
"I think the boys took Cardiff a little lightly but I always knew how much the Cardiff boys would be up for a home game in Europe.
"We did not panic at half-time it was just a case of putting some points on the board, we had a good start to the second half and when we brought a few fresh legs on we dominated."
Cardiff lost centre Gavin Evans to a head injury in the first half after he slipped and collided with Toulon full-back Delon Armitage, who was lining him up for a tackle.
Evans was stretchered off and taken to hospital for checks, while Armitage escaped punishment from referee George Clancy.
Davies said: "It was a very robust challenge, Gavin had a bit of a knock and he is okay fortunately. It was a tough challenge.
"There is more for me to take out of the game than talk about that incident. George Clancy is an experienced referee and we have to respect his decision.
"You can argue it was yellow, red, whatever you want to do, but he made the decision and you get on with it, that was not the reason we lost the game."
Davies' comments were echoed by Jenkins, who said: "I saw it on the big screen, it was high but I thought he (Evans) slipped a little bit. If someone slips in front of you it is hard to adjust, I think a penalty was fair enough.
"It was a high tackle but I don't see what else he could have done, he had committed to the tackle and once he slipped he did not have time to adjust."