A 15 minute hat-trick from Cardiff Chris Czekaj wing was the highlight, and flyhalf and man-of-the-match Nicky Robinson did his Welsh selection hopes no harm whatsoever with some flashes of brilliance.
It will have reassured watching Wales coach Scott Johnson that he has a capable deputy standing by in case Stephen Jones is not fit in time for next Saturday’s RBS 6 Nations Championship match against Italy.
The visitors, with Gavin Henson featuring at full-back, started so well, regaining possession from their own kick-off and sweeping forward for fly-half Shaun Connor to drop a neat goal.
Opposite number Robinson responded with three successful penalties before Connor dropped another goal, with the boot dominating as freezing fingers brought handling errors.
Then suddenly the night was lit up by a flash of Blues’ brilliance.
James Goode won a lineout on the Ospreys’ 10-metre line, Mike Phillips fed Nicky Robinson and the number 10 ghosted through a flat defence to score a try which he promptly converted.
Ospreys lost prop Cai Griffiths to the sin bin, but it was Henson – previously noteworthy only for dropping a high ball – who slotted over a penalty to close the gap.
But the Robinson brothers combined to fashion another Blues’ try in first half injury time.
Jamie burst through on halfway, Nicky floated a perfect cross kick and Czekaj caught the ball and flopped over.
A third score came immediately on the restart as Australian Marc Stcherbina split the Ospreys tacklers and skipper Rhys Williams fed Czekaj, who handed off Shane Williams to go over in the corner.
Visiting captain James Bater kept his side’s flickering hopes alive by wriggling over wide out but Henson, like Nicky Robinson before him, failed with the conversion.
Back came the Blues with hooker Duane Goodfield and Stcherbina featuring, before Czekaj turned Jonathan Thomas inside out to complete his hat-trick and secure a bonus point. Robinson celebrated with a wobbly conversion.
Jamie Robinson grabbed an acrobatic effort, again improved by brother Nicky, as the Blues wrapped things up.
And just to round off an awful evening for the Ospreys, lock Andy Newman was yellow-carded at the end.