The Blues put one over on the Ospreys in last night's penultimate pool game in the WRU Regional under 18 Championship at Jenner Park in Barry.
However, their 25-22 success in front of a record attendance for the competition - 1300 - does not affect the overall standings in the table.
In fact with the two sides having performed so well in the opening three months of the season, they will meet once again at the end of next month in the final at Llandovery.
With that game in mind, the Blues were understandably keen to strike a physcological blow. And they achieved that courtesy of tries from captain Jake Thomas, Christian Dacey and Lloyd Williams and three conversions and a long range penalty from Joe Deacon.
They led 15-12 at the interval with high performance manager Gafyn Cooper delighted with another excellent performance.
He said, "It was another great night for the boys. The staging of the game could not have been better and the crowd was far and away the biggest we have played in front us.
"They are a good side and made life really difficult for us, but we held on and Joe Deacon's penalty from half way earned us an excellent win."
In the other game, the Dragons recorded a 34-10 win over the Scarlets at Abertillery Park.
Cardiff Blues were crowned the Welsh champions of the Premiership Rugby 7s Series on Saturday night to book a place at the Series Final on Friday, August 8 - and you can join them with tickets on sale NOW!
Wales will tonight (Saturday) stage the first leg of the Premiership Rugby 7s Series this Saturday evening at the BT Sport Cardiff Arms Park - and tickets remain on throughout the day and right up until kick-off so you can join us for an summer night of top class rugby!
In its sixth year the Blues Cup once again showed to be huge hit throughout the region and is a great advert for the community game as each of the six finalists across the three age groups produced rugby of an outstanding level resulting in 14 tries.
Inspired Cardiff Blues enjoyed Judgement Day at the Millennium Stadium as they secured a tense 17-13 win over regional rivals Scarlets in a feisty and enthralling encounter in the RaboDirect PRO12 on Easter Sunday.