Iain Henderson has been tipped to spearhead Ireland's new breed of enforcers in the absence of key pack leaders Paul O'Connell, Peter O'Mahony and Sean O'Brien.
Ireland will be forced to reshuffle almost half their pack for Sunday's World Cup quarter-final with Argentina at the Millennium Stadium, with O'Connell and O'Mahony out of the competition and O'Brien banned.
Captain O'Connell's Test career is over after 108 caps, the 35-year-old set for hamstring surgery, while flanker O'Mahony needs an operation on torn knee ligaments.
O'Brien has been banned for one match for punching France's Pascal Pape, leaving scrum coach Greg Feek backing bullish back-five forward Henderson to help fill the leadership void.
"All of them need to step up and become leaders in their own right now," said Feek.
"We can't wait for someone to do things, we have to stand up and do it.
"Iain Henderson did well off the bench against France and hopefully he can keep his form going.
"I've said before some games you need guys in from the start and others for the same guys to make a big impact off the bench.
"However it falls they all have to take the game by the scruff of the neck."
Ulster star Henderson has excelled at lock when called into action across the World Cup, imposing himself physically and coming of Test match age.
Ireland had hoped to employ the 23-year-old at flanker in the closing stages of Sunday's 24-9 victory over France in Cardiff, but had to rethink that plan after O'Connell's injury.
Donnacha Ryan could now slot in at lock for O'Connell, to offer another heavyweight option in the front-five.
That would allow Henderson to replace O'Mahony at blindside and Chris Henry to come in for O'Brien at number seven.
Scrum specialist Feek has admitted Argentina will pose Ireland's biggest set-piece challenge of the tournament so far, with the likes of Leicester loosehead Marcos Ayerza singled out for praise.
Ireland bested the much-vaunted French in the scrum last weekend, but Feek does not anticipate such a straightforward challenge this time around.
"Argentina have come into the World Cup under the radar a bit, but they have got a well-balanced side," said Feek.
"We are under no illusions that this weekend will be our biggest test so far.
"Marcos Ayerza is their big rock, I suppose.
"Since coming back to the new laws, I think he has come back to the fore, and the World Cup has shown that if you don't get it quite right, anyone can hit you.
"It's a real mental thing now and with Argentina, they look really good.
"I think the combinations that Argentina have got have been together a bit longer than France in the front-row.
"They seem to be a bit more used to each other.
"I think the French were still dangerous, you saw that, but Argentina really know what they want to do and it is going to be a really tough challenge."