Gethin Jenkins will make his full RBS 6 Nations Championship debut on Saturday - by playing out of position against the Grand Slam-chasing Irish.
Promising Pontypridd prop Jenkins has been thrown in at the deep end for a Millennium Stadium showdown which Wales must win, otherwise they will go to France on Saturday week facing an embarrassing tournament whitewash.
Jenkins, normally a loosehead for his club, packs down at tighthead in a much-changed Welsh team following the 30-22 defeat by Scotland 12 days ago.
Wales coach Steve Hansen has no doubt the 22-year-old can do a job, claiming: "Everything tells us that he will handle it well."
And Jenkins, whose only previous start from four Test match appearances was against Romania last November, is determined to reward the confidence placed in him.
"The tighthead role is certainly different from playing at loosehead - it is a lot harder and a lot tougher physically, although you still get the bumps and bruises at loosehead," he said.
"But I have felt comfortable at tighthead in the games I've played there. There were a couple of scrums after I went on against England, and quite a few more than that during the Scotland game.
"I have also played there once or twice for Pontypridd and, while it's going to be tough, you just get on with it."