Howley said the Wales team will have to maintain composure under pressure to mee the Springbok challenge.
"We can expect plenty of physicality on Sunday but the fitness owrk we have put in this summer will have also helped our mental preparations," he said..
"We have worked hard on our efficiency and our fitness and that certainly showed in our preparation games against England and Argentina."
Howley insisted that he and his fellow coaches are pleased what the squad has achieved so far in their summer preparations which began in June.
He said that a key message for the Wales team was to minimise the errors in the game particularly because of the kicking accuracy of Morne Steyn
"Discipline, particularly in the tackle area and cutting down on unforced errors are key to us. We have to make sure we do not give silly penalties away,"he explained.
"It will be a huge factor if we are able to show composure and of course we will have to take our chances."
He said the current Wales squad players will take confidence from their recent encounters with South Africa.
But he warned that the strength of this South African team cannot be ignored by his players.
"They're a very good side in terms of their power game and their accuracy in the set piece.
"So when we create opportunities and get behind lines we have to take our chances. It will be a huge factor if we are able to show composure throughout the game."