Which props will emerge unscathed from All Blacks' battle for the front row?

Ian Foster has somewhat of a conundrum on his hands.

While elder heads Nepo Laulala, Ofa Tuungafasi, Karl Tu'inukuafe and Angus Ta'avao were all selected in the front row for the All Blacks' July series with Ireland, injuries and a change in tack saw the former three absent from the more recent trip to South Africa.

30-year-old George Bower - in his second year as an All Black - started the season as the side's first-choice loosehead prop in the absence of the sidelined Joe Moody while Laulala and Tuungafasi shared starting duties on the tighthead side of the scrum throughout July.

Bower was again employed in the No 1 jersey in the first leg of the South African tour with the experienced Ta'avao partnering him in the front-row but after a middling performance in Mbombela, coach Foster decided to change things up by handing spots in the match-day 23 to Ethan de Groot, Tyrel Lomax and Fletcher Newell - three players who weren't even included in the squad for July.

All in all, nine props have been handed opportunities throughout the All Blacks' opening five Tests of the season - and nine props certainly won't be required for the remainder of The Rugby Championship, which will see NZ take on Argentina and Australia over the coming four matches.

Injuries to Laulala and Tuungafasi paved the way for the inexperienced duo of Lomax and the uncapped Newell to feature against the Springboks but the former two will make their returns to the field for their respective provincial sides this weekend and, as such, should be available to take on Los Pumas in Christchurch on August 27. As such, Foster will need to make the call whether to stick with the new breed of props or revert to the more experienced options.

Had Foster fallen on his sword and been replaced, a new coach may have been able to put loyalty aside and opt for the younger models but that's probably less likely with the status quo being maintained. Perhaps the biggest fault Foster has shown throughout his tenure in charge of the All Blacks is his commitment to sticking with incumbents (both players and coaches) when there's been an obvious need for change.

Hooker Samisoni Taukei'aho was used off the bench in the opening two matches of the season when it was clear to all and sundry that he should have been Foster's first-choice hooker and it came as a surprise to no one when the 25-year-old was one of the best players throughout the two Springboks clashes. His elevation into the No 2 jersey came far too late and the same could be said for the promotions of Ethan de Groot and Fletcher Newell, who Foster was almost forced to play after injuries prevented him from sticking with the tried and tested.

The likes of De Groot and Newell are young and still not yet entirely proven but they're also clearly long-term options in the All Blacks scrum. That doesn't necessarily mean they're not ready to be regularly playing big Test matches, however.

"For [De Groot and Lomax] to start in that test match, without a doubt the biggest Test that they've had in their careers, to perform the way they did was awesome," said All Blacks captain Sam Cane following the 35-22 win in Johannesburg.

"I'm really stoked for those guys, it makes for some really healthy competition going forward."

Foster was equally as pleased for the young props: "There was some new players in [the pack] that were pretty special. Ethan de Groot is not brand new but I was really proud of his game today. Tyrel Lomax, first start in a big test for him and the likes of a Fletcher Newell, a superb young man, what a place to play your debut."

Now, however, comes the real challenge for Foster, selector Joe Schmidt and forwards coach Jason Ryan: determining whether to revert back to the old brigade and send the new kids on the block back to provincial rugby for the remainder of the season, or to invest in youth.

"That's a good question," Foster said on Sunday when asked how they would tread moving forward. "[It] just keeps the pressure on - including [on] us as selectors."

With Laulala and Tuungafasi both nearing the half-century mark for Test caps, they'll likely find themselves favoured ahead of the affable Angus Ta'avao, who may well have played his last match in black earlier this month. On the loosehead side of the scrum, the situation is less cloudy with only three specialists in the squad after Karl Tu'inukuafe was omitted from the squad for the Rugby Championship. With the All Blacks XV set for their inaugural tour later this year, it could be that Foster opts to travel with an enlarged squad in November but then offloads newbie Newell for the second-string games before making a call early next year.

It's a good position for the All Blacks to be in but it means some tough decisions need to be made in the near future - and that's not necessarily something at which Ian Foster flourishes.