With European duties over for the year, attention turned back to GUINNESS PRO12 matters last Friday with Scarlets the visitors to BT Sport Cardiff Arms Park.
But they found themselves chasing the game, trailing 21-6 at half-time, while Priestland's third penalty of the match was the only score after the break.
It means the Scarlets have now failed to win away from home all season, although it was the performance in general which troubled Priestland more.
Their next chance to put things right is an away match against Ospreys at the Liberty Stadium on Saturday and the Wales fly-half knows they must make improvements.
"We have the Ospreys up next. If we play like we did in that first half next weekend we'll be facing a hiding," he told Ospreys official website.
"We all have to look at ourselves and at each other. I don't believe anyone of us can say we gave it our best (against Cardiff Blues).
"We have a lot to work on but I'm confident we can turn it around in a week.
"It was a derby - these are the games our supporters want us to win - it's disappointing that as a team we didn't give a performance we know we're capable of.
"We know that we're better than what we showed - each and everyone of us will have to improve by next week."
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