Having absorbed a fearsome Springbok opening to the game, Smith grabbed the ball when a penalty was awarded and kicked to the vacant left flank where wing Rieko Ioane's speed burned the South Africans for the opening try of the night.
Smith said they had a plan to do something similar off a lineout but it had unfolded with the penalty.
"We knew the space was there but I think I fluked it a bit," said Smith.
"I just saw their fullback in the line and I saw Damian (McKenzie) so I thought he would be a good chance, and then Rieko came out of nowhere.
"I wanted to get the game going. We hadn't had the ball much and just wanted to keep them on their toes and I saw a flat line so I hoped no-one was behind me so I kicked it hoping there were be a foot race and it turned out really well," he said.
In spite of the record nature of the win, Smith said it didn't feel like such a high margin between the sides.
"But it doesn't feel like it was that kind of scoreboard to me. It was a real physical game, they were coming at us all day.
"In the first 20 they really a physicality and a tempo that probably we hadn't seen this year. They were just going hard, coming at us taking guys out and hitting us.
"We got a couple of turnovers and were able to score tries and maybe nullify their passion for a bit and then we were able to get into a bit of work and start getting our structures going at the back end of that first half.
"Some of the individual brilliance from some of our loosies in stealing the ball and Nehe (Milner-Skudder) and Beauden (Barrett) and stuff like that was great to see.
"It's quite scary to see where this team could go," he said.
But it was the ability of the All Blacks to absorb the South African assault and then capitalise so quickly on opportunities that marked the difference between the sides.
"They were putting us under a lot of pressure but with our defensive plan we got a bit lucky with some of the balls we were getting on turnovers. Maybe not lucky... We were forcing errors which is a big part of defence. It was a bit slippery but to be able to get a turnover and score is something you dream of," he said.
Sides were at their most unstructured from turnovers it was important to be able to capitalise on those chances.
The forward effort by the All Blacks had been impressive.
"To see them stopping them again and again. They're big boys, when they run downhill they are going to win some contacts but just our ability to get to in a tackle and slow them down... I don't think they got in our 22m that much," he said.
"That's the hardest thing. You let teams get in your 22 you are going to give up anything that looks offside. It looks clinical, you're going to give away penalties or tries.
"That was quite good to see we were able to hold the fort there after Australia and Argentina got some soft tries off the ruck defence and that's something we really worked on this week," he said.
But there was not too much time to enjoy the win as he felt the Tests in Argentina and South Africa were going to be tough on the back of the travel involved.