As the All Blacks relax during their week off from the Rugby Championship, coach Steve Hansen could be forgiven for feeling a little anxiety as he waits for progress reports on Luke Romano's shoulder injury.
The Crusaders lock has played only two tests but already has become an extremely important cog in Hansen's machine.
Romano, Conrad Smith and Tony Woodcock are the only players with a question mark over their fitness.
Hansen recently referred to his liking for combining a big, physical, player alongside a "skinny" one in the second row.
With the wiry Sam Whitelock, still only 23 and a relative veteran of 29 tests, virtually an automatic selection, that puts a big onus on the 26-year-old Romano.
The other option, Brodie Retallick, 21, is in the Whitelock mould. He has also performed spectacularly during his breakthrough season and will start in the next game, against the Pumas in Wellington a week tomorrow, if Romano doesn't.
Below these three, however, the cupboard is a little bare, the huge hole left by Brad Thorn's departure not quite filled yet.
Craig Clarke, the impressive Chiefs' captain, has been included in the All Blacks' recent Auckland training camps, officially because the medical staff are monitoring his knee injury.
Nevertheless, he wouldn't be getting such care if he wasn't on Hansen's radar and appears to have overtaken Jarrad Hoeata as the next best.
Ali Williams is an incumbent, but also has a knee injury which he aggravated in the second test against Ireland in June.
Already struggling for form with the Blues this season, his best hope of a playing return after surgery is for Auckland in the second half of the ITM Cup.
Whether the 31-year-old makes the end-of-year tour remains to be seen, although Hansen is a big supporter.
On Saturday against the Wallabies, Romano took a knock to the shoulder that has troubled him this season.
He offers a ball-running and defensive edge that neither Whitelock nor Retallick can quite match and Hansen will be eager to retain him against the physical Argentines.
And Hansen won't be the only one. With only three locks named in the squad, the coach has raised the prospect of Kieran Read being press-ganged into the second row, which the No8 won't be overjoyed about.
The test in Wellington will be a significant one for centre Smith, if he does recover from his detached retina as Hansen believes he will.
His quiet organising will be important in order to get the best out of Ma'a Nonu, returning to second-five after Sonny Bill Williams' exit.
Prop Woodcock is on track to return from a rib cartilage injury, and Hansen will be hoping for similar news on Romano.