Steve Lawrie's back injury has failed to respond to treatment, which is why Brown could be called into action. Scotland's interim head coach Scott Johnson was up front in admitting that they will try to get Scott Lawson, the starting hooker, to play the full 80 minutes, but if Brown does get on it would be a remarkable turnaround for the former under-20 captain whose career looked over two years ago when he was axed from the Edinburgh club academy at 22 after a neck operation.
"You talk about his life, a farming boy, a tough boy," said Johnson. "Tell you what, he is an impressive kid. It is a big ask, let's not kid ourselves, there is something there, there is no doubt about that."
Brown has managed to get his career back on track and had just signed a full-time contract with Glasgow. Still, it shows the severity of Scotland's front-row injury problems that he is probably no higher than seventh choice in his position and yet could be about to win his first cap.
Johnson added: "That is the way it is and we can't get away from that. Out of this, it might be the greatest learning curve we have got; necessity is the mother of invention. We have to find out about him, if he gets out there it is not ideal, not ideal for him and certainly not ideal for us, but a lot of good will come out of this. We can't buy this experience."
Nor do Johnson's problems end at hooker, with Euan Murray, the tighthead prop, also struggling to overcome a hamstring problem. He has taken part in scrum sessions over the last two days without any adverse reaction so Johnson is more hopeful in his case, but will not make the final call until moments before the game.
The rest of the squad came through their final session without any obvious difficulties, realising that they are facing one of the toughest games of their careers if they are to salvage Scottish pride after their mauling at the hands of Samoa last week.
In that game, they buckled under the ferocity of the physical confrontation, but the coaches have spelled out that if the same thing happens again when they face the Springboks, they could be in for a hiding.
That puts huge onus on players like Jim Hamilton, who will leave the squad after this game to be with his wife at the birth of their second child, who has been brought into the team specifically to add that physical edge.
"We all know what the game against South Africa is going to hold," he said. "They are a very physical team, one of the most physical in the world, and they're good at what they do. There have been a few changes this week. We (Hamilton and Tim Swinson, the other lock) have been put in there to do a job. We're well aware of the challenge in front of us and what's going to come."