Ross still the front-row boss as Schmidt puts 'World' in focus
He may be turning 35 next month but tighthead's health is vital to Ireland
Depending on Rory Best's ability to recover from his calf troubles, Mike Ross could be the last man standing on Saturday evening.
Joe Schmidt has used 48 players since taking over as Ireland's coach, but the front-row duo are the only two to have started all 10 games. If the hooker doesn't make it, the Corkman will be out on his own.
He is a somewhat unlikely linchpin of the New Zealander's game plan, but his ability to provide the national team with solid, reliable ball from the scrum will be key to any success this November.
Rivals are emerging, but Ross remains the most important man in the building. Nathan White and Marty Moore might have provided competition, but they suffered injuries; the others simply don't look ready.
Thus, he is set to be pressed straight into the action against the second best team in the world this Saturday despite not having played for more than a month due to a groin injury that kept him out of Leinster's European games.
He only returned to full training yesterday, but will be expected to perform on his 42nd appearance in green.
"He has got one game to get into it this time and it's a big one," Les Kiss said. "That is all there is to it."
The reliance on one tighthead prop pre-dates both Ross and Kiss and goes back to the John Hayes era. Ireland have been blessed to have had two No 3s with the Midas touch when it comes to avoiding injury given the lack of depth in the position.
Their reliability has masked a shortage that has lurked beneath the surface and caught the team out from time to time.
The IRFU have had to be creative in their approach and go abroad for the kinds of specimens needed to step in, hence the presence of Nathan White and Rodney Ah You at Connacht and Michael Bent at Leinster.
Of that trio, White looks the most likely to be at next year's World Cup, but - at 33 - he is hardly a long-term solution. Ulster's Wiehahn Herbst is another project player but he won't qualify until 2017 and is blocking Declan Fitzpatrick's path to a starting jersey just as Springbok BJ Botha keeps Stephen Archer out of Munster's team.
It is Leinster duo Moore and Tadhg Furlong who look the most likely to fill the gap.
Moore emerged last season and played in every Six Nations game as Ireland claimed the crown, while Wexford native Furlong has long been recognised as the real deal in waiting.
He has been involved this week, but his provincial coach reckons he has some way to go in his development before he is ready for Test level.
"If you were to put a number on it, he'd probably need 20 games. It's a little bit higher in the tight five, higher again in tighthead. It's a long-term development curve that those blokes are on," Matt O'Connor said.
"We want to manage that as best we can and the province has got a good track record in terms of Jack McGrath or Marty Moore in making sure we stay patient and set them up for a long and successful career."
Ah You, Archer and Furlong have been in camp this week and the young Leinster man is set to be released today, with the New Zealander set to back Ross up off the bench.
Kiss says those players need to make the most of the chances they get.
"You don't have the ideal scenario to be able to expose every tighthead or any player in any position to the highest level," he said.
"Overall when we discuss the provinces and the work that they are doing, they are doing their best to make sure players are ready for that next level and at some stage you have just got to make that step and you find out from there."
South Africa are a daunting prospect for any novice and the 'Boks are paying the Irish set-piece due care even if they'll be well aware of Schmidt's scrum issues.
"The Ireland statistics speak for themselves," scrum coach Pieter de Villiers, who played 69 times for France, said.
"They have 100pc record in terms of scrum success for this year, so we do respect their scrum, a lot. They have been very solid in the Six Nations and in terms of their tour to Argentina.
"We know we will be up against a solid unit and that is a great challenge after us having spent the latter part of the Championship doing well and having had these two weeks to prepare. I think it will be a good contest."
With Tendai 'Beast' Mtawarira and the du Plessis brothers in town after providing the platform for their side's win over New Zealand, the battle lines are drawn. Kiss is backing Ross to come through despite the concerns over his lack of game time.
"One of the real pleasing factors over the last seven or eight days that we have had our camps is that he has had a major input into the whole scrummaging meetings etc," the defence coach said.
"He has worked with Greg Feek, he has taken that little bit of leadership in it even though he hasn't been able to train fully up until the last couple of times, he is really on top of it. I'd imagine he is relishing the challenge."
Ireland hope he can deliver once more.
The men behind Mike Ross
Rodney Ah You
Out of his depth in Argentina last June, but the New Zealand-born 26-year-old is likely to get a second chance this month. Used largely off the bench by Connacht, has impressive physical presence. Minutes played this season: 322
First involvement since struggling badly against Australia last November. Is swapped in and out with BJ Botha at Munster, but usually on bench for bigger games. Minutes played this season: 183
Called into the squad to train this week and a highly-rated prospect for the future. Possibly too soon. Minutes played this season: 171
Looked the part against the All Blacks last year, but poor injury record. Minutes played this season: 87
In the treatment room
Nathan White was expected to make his debut this month but a freak arm injury ruled him out, while Martin Moore was Ross' back-up for province and country last season but has played just twice this season.