Scarlets head coach Wayne Pivac attributed Saturday's 29-12 loss against Racing 92 to a failure to follow the game-plan and their opponents' physical dominance.
After the defeat to Northampton Saints in the opening round of the Champions Cup, Scarlets had hoped to use their home form to their advantage and secure a vital win over the Parisian outfit at Parc y Scarlets.
Four first-half tries for the visitors with no response from the home side made it look an impossible task but Scarlets came back to score two tries in the second-half but had left too much to do to secure a result.
"We're disappointed with the first half, the game got away from us," said Pivac.
"We didn't want to be playing too much in our half and we didn't execute our game-plan in the conditions.
"We certainly wanted to kick more and get field position. They were able to get the ball away in attack and get behind our defensive line.
"We came up against a big heavy pack and it has shown us the standard we have to aspire to.
"They were better than us and deserved their win. It keeps us grounded, we've got to go away and keep working hard. It's a big learning but we have to move on and not look for excuses."
Scarlets head back into PRO12 action next weekend with a home game against Zebre on Sunday 29 November.
Pivac said his side will look to rebuild momentum in the domestic tournament before another couple of rounds of Champions Cup action before Christmas.
"It was nice to get a couple of tries but it's a performance we'll certainly have to take a look at," he added.
"I don't think we were as physical as we have been. We've got to refocus now, go back into the PRO12 and look to improve on that performance against Zebre next week."