Rennie revealed he had flagged an issue with the Bok scrum with World Rugby. He claims the Bok front row is walking around, which changes the angle and allows them to get the upper hand.
It comes across as sour grapes after the All Blacks had no answer to the Bok powerhouse in the opening Test at Ellis Park, conceding six penalties in the process.
A week later, a different referee, a narrative put out in the media and a second-choice Kiwi prop, the Bok scrum only got one penalty at scrum time from referee Angus Gardner. There were no less than six scrum collapses on the All Blacks' ball during the match, with each one being reset.
Speaking to the press after the match, Erasmus vehemently denied Rennie's accusations in an impassioned response.
"We've been playing with this pack of guys together for years and it's the first time in history that people are talking about us walking around," he told the media after the Boks' 33-26 victory.
"So why would we all of a sudden start walking around now? The first six scrums in New Zealand's half, they had every single one collapsed. And it was reset, reset, reset, reset. So why is it only on their ball that the scrums collapse every single time?
"So don't come with that nonsense and say we're walking around and try and put things out in the media. If you just want to start moaning about stuff like that, then they're under pressure.
"So if the referees get caught up by that, then there's obviously a plan to get that message out. And then we don't want to stay quiet and just say, 'Oh, you're right, we're walking around'.
"We're not f**ing walking around. We scrum straight. So, you know, we've never, ever, ever been accused of walking around. So I don't understand."