The 2014 SA Player of the Year said that South Africa had been playing against New Zealand twice a year for so long that there were few surprises.
"The coaches have already sorted out the way they want to attack and defend and what plays they want," he said. "So as a player it definitely comes down now to mental preparation, how you get yourself ready for Saturday."
The Boks have a resident sports psychologist, Dr Pieter Kruger, whose business it is to read the body language of the players.
"If he suspects you are not 100 per cent he will sit down with you and put you in the right direction," Vermeulen said. "It is about making sure that every individual is perfectly prepared to play his part when needed."
Importantly, Dr Kruger has been working with the Boks where they have often been found wanting this year - the third quarter, after having built up a good half time lead, only to enter a flat spot.
"We have to accept that we cannot dominate a top side for 80 minutes, they will also have their period of ascendancy, but during that time you have to find ways to keep the scoreboard ticking, because it is scoreboard pressure that has seen us implode in the final quarters of games against the All Blacks and Wallabies."