On Saturday, holders Leinster begin the defence of the Heineken Cup in Montpellier - last year's surprise Top 14 finalists - and O'Brien is only too aware of the role he must play in the south of France.
"It is a role I like," said O'Brien. "Brian is a big loss there, but it gives the younger lads a chance to step up to the mark.
"At club level, the likes of Fergus McFadden and Eoin O'Malley, they are both good at talking as well.
"We have enough experienced players there on the field, we've Leo Cullen there as well. Brian will be there anyway, he'll be off the field, he'll be chipping in with his say as well.
"It is not as if he has gone away for good or anything."