John Lacey will be the man in the middle at kick-off in front of a 10,000 sell-out crowd as the Warriors aim to reach what would be a dream Celtic Park final against Leinster or Munster next Saturday.
Neutral officials are usually deployed, though not mandatory, in cross-border matches in what is now a Celtic, Italian and South African competition, and eyebrows have been raised that former Ireland A international John Lacey, 45, has been handed the whistle for last-four clash.
Elsewhere, Scottish ref Mike Adamson will lead an all-Scottish team of officials at tomorrow’s Leinster-Munster clash, while Welsh referee Nigel Owens is a touch judge at the Ospreys-Scarlets Heineken Champions Cup play-off match in Swansea.
“I guess it comes down to who. Maybe it was Nigel Owens and a Welsh contingent could have done it, perhaps?” wondered Rennie.
“But I guess he [Lacey] refereed a quarter-final and if he [Owens] is No 1 they’ve probably got him down for the final.”
Rennie was speaking after naming 2015 Pro12 title-winning hero DTH Van der Merwe in his starting line-up for tonight after the Canada wing’s speedy recovery from a shoulder injury that was initially thought to have ended the 33-year-old’s season.
Callum Gibbins will skipper the side, featuring for the first time since a head injury suffered during the Saracens defeat in the Heineken Champions Cup quarter-final in March, with fellow back-rower and co-captain Ryan Wilson on the bench.
Rennie stressed that the appointment of Irish officials had played no part in this week’s build-up.
“We haven’t even discussed it with our players. John Lacey is very experienced, he’s got good men on the sideline who he trusts, so that should help him,” said the Kiwi. “This is about our performance – there will be no talk about who’s refereeing. It is out of our control.
“We’ve just got to make sure we paint the right pictures and perform at our best. Any questions around that stuff are probably irrelevant.”