Leinster officials are optimistic that Lions centre O'Driscoll will be fit to face Newport in Dublin on Friday evening and there were similar reports emerging from the Ulster camp this morning regarding fly-half Humphreys' status.
O'Driscoll has a badly damaged finger sustained in Ireland's 20-14 triumph over England at Lansdowne Road last Saturday and there were concerns that he would have to withdraw from the Leinster squad for Friday's Pool 6 tie at Donnybrook.
Team manager Ken Ging said today: "At this stage we're waiting on the medical report but that can't be done until the swelling on his finger has gone down. "It could be dislocated, we just don't know, and won't know until Thursday; but we're optimistic he'll be okay for Friday's game."
Ulster team manager Joe Miles is also confident his man will be lining up on Saturday when the 1999 European champions meet Stade Francais in Paris.
Humphreys sustained an ankle ligament injury against England which forced his retirement but Miles said: "We are monitoring David's injury every 24 hours but if the rate of recovery which has taken place so far continues then we would expect him to play at the weekend. We will make a definitive decision on Wednesday but maybe even as late as Thursday."