A forlorn Brodie Retallick watching All Black training from the sidelines at Wits University on Tuesday afternoon local time signalled two things.
The first is that he hasn't fully recovered from his head knock in Argentina and almost certainly won't play at Ellis Park; second, that the All Blacks have become world leaders in their management of players with concussion.
Retallick, who came off in La Plata after a suspected concussion in the second half, made strong progress. There was optimism that, having been alert and in good spirits on the plane to South Africa, he would be passed fit to play.
But he didn't feel quite right when he awoke on Tuesday and wasn't deemed well enough to train.
His probable absence will be a significant loss for the All Blacks. Retallick has been in superb form all year and established himself as arguably the premier lock in world rugby.
His ball-carrying and physicality at the collision have been critical ingredients. In a different age, given the importance and likely nature of the test against South Africa, Retallick probably would have played this weekend.
He could easily have hidden his symptoms - said nothing to anyone. Just as easily, the coaching staff could have convinced themselves he would be fine by Saturday.
His symptoms are mild, he's not obviously struggling and it's a huge game ...
But that age is history. The instant Retallick wasn't able to train on Tuesday, his goose was pretty much cooked.
If it had been a dodgy hamstring, the selection door would have been kept open. They would have delayed a decision - most likely bracketing him with Jeremy Thrush.
But it was his head, and with that there is zero leeway. The All Blacks have been steadfast in their health-comes-first policy on concussion. If there is a tiny doubt, the decision is made early in the week that the sufferer won't be available.
Even though there is a reasonable chance Retallick will be passing all the concussion tests by Friday - it won't matter: the All Blacks aren't interested in taking any risks with any of their players.
That's why the coaches weren't sure if Wyatt Crockett would be available either after he suffered a nasty facial laceration against Argentina.
