Ahead of facing England in the Six Nations (today, 4.50pm), Ireland head coach Joe Schmidt has admitted that the loss of Les Kiss to Ulster has left a hole in his side's set-up.
Kiss served as Ireland's defence coach under both Declan Kidney and Schmidt before moving to Kingspan Stadium to serve as director of rugby after the most recent World Cup.
The Australian, whose innovations during his time on the Test circuit included the development of the choke tackle, will eventually be replaced by Andy Farrell, but the former England coach cannot start work until after the Six Nations thanks to an agreement with today's opponents.
Forwards coach Simon Easterby has been assisting during the transition but Schmidt says he has missed Kiss's familiar presence at their Carton House base.
"It's been a mountain of work I've got to say trying to do both sides of the ball," he said.
"I think Les Kiss is world class.Not having him has been a bit of a hole for us. Simon Easterby has stepped up for us. He's an intelligent guy, he's an intuitive guy.
"Between us we've bounced a fair few ideas around.
"Richie Murphy, even when Les was here, has always been a sounding board for what opposition teams are doing."
Schmidt remains very much in contact with his former colleague, making frequent checks to Belfast to ascertain the level of form displayed by Ulster's Ireland contingent such as debuting centre Stuart McCloskey.
"I have spoken to Les and to Neil Doak and spoken about the various aspects of Stu and Luke Marshall and other players as well.
"You're always looking at how Jacko (Paddy Jackson) is going, how Craig Gilroy who was in camp this week has gone. There's always an open line of communication."
Farrell's successor with England, Paul Gustard, has come in from Saracens and Schmidt admits that McCloskey impressed him when facing the English champions twice this season.
While Ulster lost both games, it was McCloskey's break at Allianz Park that created a try for Luke Marshall and offered brief hope of a win that would have greatly altered their Champions Cup campaign.
"There's so many things that go into a selection. Part of it is Stu's provincial form, and part of that was against Saracens home and away. He caused them some problems.
"At the same time, the Saracens attack, of which we will see a few of them, they caused a few problems as well so there's counter-balancing there.
"You try to look as forensically as you can in to what you think might work and who has worked in the system before."
On Farrell, Schmidt said there was never a possibility the former rugby league star would be mined for information ahead of today's clash.
"One of the reasons we want him in our environment is because we think he's going to contribute really well. The one thing we haven't done, I haven't spoken to Andy.
"I think you've got to honour agreements that are set in place.
"In the lead up to this game, it's really important that we go it alone and try to work out how best to put our defence together and try to ascertain what they're going to throw at us."