Joey Carbery won't just cover the scrum-half position against Russia - but also full-back, centre and out-half.
The Munster no 10 trained alongside Luke McGrath yesterday to be ready to step in if McGrath has to come off at any stage in Kobe.
Ireland only have two recognised scrum-halves in Japan - Carbery's provincial colleague Conor Murray, who steps out of the matchday squad this week after starting the first two pool games - and McGrath.
“Joey trained at scrum-half on and off probably three or four times so far," said Ireland boss Joe Schmidt.
“On the back of last weekend where we ended up with a scrum-half (McGrath) on the wing (against Japan), I think Joey mightn’t be the worst replacement to have because he’s got a bit of versatility.
"He could even slot in at 12 and do a really good job and would give us a bit of two-sided attack and that wouldn’t be the worst thing either.
“So having him on the bench is potentially a bit of a bonus for us.
"If things work out well it would be nice to give him a little bit of time at scrum-half, just to have him be a little bit comfortable there not having played it since he was really probably a schoolboy".
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