The obvious answer is history. The Springboks have proved themselves as the ultimate closers in rugby union.
When they won their second consecutive World Cup last year, they did it by clinching three knockout games by a point.
They had also beaten Scotland in their past eight meetings.
Scotland actually handled the infamous 'Bomb Squad' well, as the seven forwards on the South African bench came on earlier than expected, almost testament to the hosts' work up front.
But former Scotland and Lions prop Peter Wright knew the script when Russell nailed the fifth of his penalties at Murrayfield.
"South Africa are going to close up shop now," he said on Sportsound. "They will try to be really physical, force penalties and get territory that way."
From the restart, centre Lukhanyo Am extracted a penalty at the breakdown and Handre Pollard smashed a penalty 40 metres down the pitch into Scotland territory.
A stray Matt Fagerson arm at the resulting line-out then led to another penalty, and Pollard made sure it was a seven-point game again.
The Boks went on to add another 10 points in the final 15 minutes without conceding.
As they say, it is one thing knowing what is coming but it is quite another knowing how to stop it.