Ospreys backs coach Gruff Rees felt his side lacked the necessary control as they started their Heineken Cup Pool One campaign with a damaging 19-9 home defeat to three-time winners Leinster.
The Ospreys will head to Franklin's Gardens next weekend knowing another defeat will leave them facing an almighty task if they are to reverse the recent trend of Welsh sides failing to reach the knockout stages.
Rees said: "At key moments we made bad decisions. We were not smart under pressure, and they were the opposite. They did the right thing at the right time.
"We worked really hard to try and get some attacking momentum but there were just some key moments.
"We had a penalty at 13-9 which we took quickly which was unforgivable, and it meant it went to 16-9 and we were back under the pump.
"We had a couple of opportunities where we could have turned the tables on them but we did not look after the ball, we were too shallow, too lateral in attack. It meant they won the race to the breakdown and they killed us there.
"We have got to pick up this week and have a training programme with the right amount of rugby detail, but also get a smartness and urgency into our game because at times we had no emotional control, which was disappointing."
Captain Alun Wyn Jones was also unhappy at a scrum decision during the first half where his side were penalised having had the better of the set-piece battle up to that point, and suggested the new scrum regulations this season are not as effective as he would like.
"It was my call to go for the scrum. A few boys did not want to but I felt we were on top and had the ascendancy," he said. "The next thing you know it shifted and we conceded a penalty.
"I don't want to say the scrum is becoming a lottery but it feels like it is going back to how it was."
Leinster coach Matt O'Connor, meanwhile, was delighted to have won on the road while denying their hosts the crumb of comfort a losing bonus point may have provided.
"The boys fought hard and addressed most of the issues that let us down last week against Munster and it was a pleasing result.
"We were pleased to make sure they did not pick up a bonus point as it could be important. Cup rugby is about getting what you can out of each contest and making sure the opposition get as little as possible.
"It was a pretty intense contest, a great game of rugby. They had some key passages of play where they looked dangerous and credit to our guys as we defended incredibly well and made sure they came away with nothing.
"That was probably the difference in the end."