The Blues secured their place in next season's Heineken Cup with a hard-fought 20-12 victory over Magners League champions Munster.
However, injuries to two of their number provided further scares for the British Lions management following the loss of Tom Shanklin last Wednesday.
Even before kick-off, Leigh Halfpenny felt a twinge in his hamstring and opted to pull out.
Then, early in the second half, centre Jamie Roberts - wearing the same number 12 shirt occupied by Shanklin in midweek - left the field with a shoulder injury, though he did so at a trot and unaccompanied by medical staff.
Afterwards neither man seemed too worried, but Lions coach Ian McGeechan will be waiting for reassurance after further checks.
The Blues commanded the opening exchanges but lacked the finishing touch. Fly-half Nicky Robinson even missed two kickable penalties, before spurning a third opportunity and going for position near the flag.
It paid off, superb handling along the line - particularly by Chris Czekaj, an emergency full-back following Halfpenny's withdrawal - let Tom James trot in on the left.
Munster, a man short after flanker Nick Williams was sin-binned, were under pressure for long periods.
But the broke downfield, with full back Denis Hurley leading the way, and battered at the home line until number eight Denis Leamy stretched over.
Robinson finally landed a penalty in first-half injury time, but the three-point interval margin did not reflect the Blues' dominance.
Early in the second half, the home side lost Roberts and then almost conceded a try when flanker Niall Ronan raced clear, but a knock-on ruined Munster's chance.
The Irish province were showing greater urgency and the Blues needed the TV official to rule that first Leamy and then centre Barry Murphy were held up over the line.
Their efforts were eventually rewarded when right-wing Kieran Lewis crossed in the corner and Jeremy Manning converted.
But, in a mirror image of the first half, the Blues scored on their first visit to the Munster 22 since the break, prop Gary Powell claiming the touchdown.
The video official then voted against the Blues, ruling that Robinson had knocked on after winning a chase after a Martyn Williams kick.
But replacement Ceri Sweeney made sure of the win with an interception try, converted by Robinson.