He went into the Test cold, never having faced South African sides in Super Rugby.
"It was pretty cool to be able to face them tonight."
It also helped that the All Blacks won a penalty at his first scrum after replacing Ethan de Groot. He didn't know if he could claim some of the glory; Nepo Laulala on the tighthead side forced the penalty when his opposite, Thomas du Toit, was penalised for hinging.
Williams said, "He's a great scrummager. I'm not too sure. I was seeing stars from the scrum, that's how hard it was. I was just happy to stand up and the penalty was on our side."
Williams admitted to his 20-minute stint being enjoyable and feeling better after the final whistle than he thought he would.
"The game was faster; the lungs were blowing a bit out there. But it was fun.
"It was quite refreshing to play someone other than from New Zealand and Australia.
"I love winning, bro. You don't go out there to lose, so when that last whistle blows, you've won; it makes the night even better.
"My head's running right now, but I'm sure once I sit down with the family and friends, and look back on the week, it's definitely special."
The All Blacks next face Australia in Melbourne on Saturday 29 July at 9.45pm NZT in the final match of the Lipovitan-D Rugby Championship.