Leinster are concerned enough about the prospect of losing their exalted European status without also worrying whether one of their own leading lights is about to be ceded.
As his team-mates recuperated from their success against Scarlets by resting up last Sunday, out-half Jonny Sexton was in Paris for discussions with Racing Metro about a possible move away from the back-to-back Heineken Cup champions.
The player's motives are incontestably honourable – it's not his fault that the timing of rugby contract negotiations leaves a lot to be desired. And Sexton's current discussions – as you may have heard – are freighted with massive implications for player, club and country.
Little wonder, then, that the Blues' preparations have been slightly discommoded by all the fuss.
"Oh, is he leaving as well?" smiles Reddan (right), knowing full well that O'Driscoll's mercifully fast-healing ankle is now the centre of inquiry. As a pointer towards how this closely knit squad can attempt to deal with the distractions thrown up by the ongoing impasse in Sexton's career choice, Reddan's calm demeanour offers a vital clue.
Composure will be key; on and off the field. Leinster abandoned so much of their cool, calm and collected approach once they had earned the bonus point last Saturday against submissive opposition; by the time they roused from their slumber, it was too late to re-energise their try chase.
Hence, they still remain behind the eight ball in terms of qualification despite collecting all five available points last Saturday. A win is the minimum requirement for the reigning champions this weekend in Exeter, while five points will probably be needed along with favourable results elsewhere.
That winning alone probably won't be enough sums up Leinster's whirlwind and disjointed campaign. And still they cling to vestiges of hope. After all, Reddan can remember all too clearly back in 2009 when his then Wasps side were coursing a bonus-point in their final game with all their might, only to lose in Castres when, it later emerged, a routine win might have sufficed to earn a quarter-final.
Ironically, Wasps' failure to deny Leinster a week earlier had infused them with a sense of panic, as they assumed Leinster would thump Edinburgh.
They didn't, and the moral of the story is never assume. And never panic. On that dramatic final day in Castres, the star-studded two-time champions – Shaw, Betsen, Cipriani et al – were winning with five minutes left when full-back Mark van Gisbergen fluffed a try-scoring chance, before seeing his opposite number Thomas Bouquie scoot past him for the winning try just moments later.
Agony and ecstasy on the final weekend of the Heineken Cup pool stages is always guaranteed – often in the same stadium and often within seconds of each other.
"We went chasing big time for the next two tries and we conceded a late try and lost the game," Reddan recalls of the Londoners' exit.
They – like Leinster are now facing – were eliminated at the pool stages as Heineken Cup champions – indeed, they remain the only side (twice) to succumb to such an ignominy.
Leinster would subsequently win their first title in that 2008/09 season; that they would eventually repatriate the Limerickman to help them win two more numbed the pain of that agonising exit.
"We later found out that a win would have done us without the bonus point," says Reddan (pictured). "So we know that anything can happen next weekend.
"One of our main rivals are Montpellier and they will have played already so that will help us a little bit in terms of knowing what we have to do.
"But unfortunately the way the weekend is set up, with Munster knowing exactly what they have to do on Sunday, we really have to get the win first. There's no such thing as piling on tries against Exeter. They're an extremely competitive team. They'll be looking to win this game.
"Even if we didn't need a bonus-point win and had our destiny in our own hands it would be very, very tough."
Competition debutants Exeter essentially have little to play for other than pride before their faithful fans, as they face into a determining domestic run of games which they hope can propel them into the Heineken Cup for a second successive season.
Reddan sees danger in the home side's relatively carefree intentions. "They're a very determined side," he adds. "You can see the way they play they're very much together. It's probably the characteristic that makes them toughest to play against.
"They might try a few things but they've an excellent coach in Rob Baxter. Rob is a man who respects the basics very well. They want to win a Heineken Cup match.
"They beat Llanelli there and did well against Clermont for a long time. They'd love to beat us this weekend, there's no doubt about that. That's going to be the toughest thing about it. They're a bunch of guys who are very committed and know what they're doing."
Their togetherness is unquestioned; Leinster's camaraderie will be fiercely tested as never before in Sandy Park this Saturday as they plot one of this marvellous competition's greatest ever escapes.