First half tries by Dane Blacker and Harri Millard was not enough, as Cardiff Blues Premiership Select suffered a 70-12 loss to Doncaster Knights in the British and Irish Cup on Saturday.
The hosts secured a 35-12 lead at the interval, but the young Blues side failed to mount a comeback, as Doncaster crossed for a further five unanswered tries during the second half at Castle Park.
Justin Burnell's side are set to welcome the Knights to Pontypridd's Sardis Road on Saturday for the reverse fixture (KO 2.30pm)
It was the perfect start for the home side, as a penalty allowed former Cardiff Blues outside half, Simon Humberstone, an opportunity to kick to the corner.
A series of drives were forced infield by the Blues defence, but the pressure paid off for the Championship-outfit, as Curtis Wilson crashed over from close range.
The visitors looked to bounce back immediately as Harri Millard made a break in midfield, but the final pass to the support was off-target, giving Doncaster the chance to clear their lines.
The missed opportunity proved costly as, moments later, Doncaster were over for their second through Mat Clark, with Humberstone converting.
The outside half was back on the tee five minutes later as a loose ball from a line-out was gathered by Nick Civetta. The lock made a break and found support from Tyson Lewis, who ran clear for his side's third of the afternoon.
Burnell's side struck back as Dane Blacker found a way through for his side's first try of the game, with Ben Jones converting.
But the young Blues side were dealt a blow as Doncaster Knights broke and found themselves under the posts two minutes later to immediately regain their 21-point lead and secure the bonus point.
Cardiff Blues PS were reduced to 14-men as James Beal was sent to the sin-bin for killing the ball in a ruck, and the home side secured their fifth try of the afternoon, as a collapsing maul resulted in a penalty try.
Harri Millard gave his side hope of a stunning comeback as he crossed in the corner during the latter stages of the first half, but seven minutes into the second half, the power of the Doncaster pack showed again, as Jason Hill touched down from the base of a drive.
Joe Sproston, Michael Heaney, Tom James and Matt Challinor also got on the scoresheet during the second half, as the reliable boot of Humberstone put his side's tally for the afternoon up to 70 points.