The Springboks rallied from a 10-point deficit with 12 minutes remaining to defeat the All Blacks 31-27 in Johannesburg on Saturday.
They are now chasing a fourth successive win over their greatest rivals for the first time since they claimed six victories in a row between 1937 and 1949.
Second-placed New Zealand need victory to keep their Rugby Championship hopes alive and Blackadder believes there is belief in the squad they will do so as they trail the Springboks by eight points on the table.
"We are disappointed we could not finish the job but we had a lot of fun out there. We are focussing on some small margins," Blackadder told reporters on Monday.
"We could not close it out the way we wanted to and that is our focus. We needed to keep playing footy.
"Whether it was through errors or discipline, they got back into the game and into our half. For us it is about nullifying that. To be squeaky clean and not letting them play the way they want to.
"We are excited because we know we were close in that game. The motivation is high to get it right this weekend."
Blackadder believes protecting the ball on the floor will be vital for both teams.
"The breakdown will be an important aspect, we need to take away their guys who can get over the ball. And then just finishing what we start. Two simple things but they will go a long way (to winning)."
There has been talk in recent times of reintroducing full tours between South Africa and New Zealand from 2026, with midweek matches against club teams and four tests.
Blackadder would relish the opportunity and concedes South Africa’s exit from Super Rugby to play club competitions in Europe has been keenly felt.
"It would be wicked," he said. "It is such a good place to play rugby, as an international player this is where you want to be and the matches you want to be involved in.
"Generally everyone misses the South African games and tours (in Super Rugby). It is gutting it hasn’t continued."
