Head coach Dai Young had made it clear that his Lions players would be rested if they so wished as soon as a place in Europe's premier domestic competition had been secured.
The Blues had six players named in Ian McGeechan's 37-man squad but centre Tom Shanklin has now been withdrawn after injuring his shoulder in last week's win over the Dragons.
Young is keen to ensure none of his remaining Lions suffer the same disappointment and will therefore only pick them for the club's two remaining league games if the players themselves ask to be selected.
Leigh Halfpenny, Gethin Jenkins, Jamie Roberts, Andy Powell and Martyn Williams will all be given permission to miss the home matches against the Scarlets and Edinburgh, although Jenkins has hinted that he may wish to continue playing.
"From my point of view I'm quite comfortable with not fielding them for the next two games," said Young.
"I certainly won't be even thinking about playing our Lions. I wouldn't risk any injuries with them.
"It'll be over to them really, but from our point of view we needed them really to get points to be in the Heineken Cup. After that, it's pretty much left to them.
"Gethin has already mentioned that he might want to play to keep his game-practice going."