"This is important and although we are not constantly talking about it, we know we have a possibility to go down in history with this winning streak," coach Vicente del Bosque told a news conference on Friday.
"These kind of records can never be questioned. They are hard fact that will be there for all to see."
If Spain avoid defeat they will also match Brazil's mark of 35 consecutive matches without losing.
"Once you have winning form it becomes important to keep up the momentum ... and make the team unbeatable," said reserve goalkeeper Pepe Reina.
"This is an ideal situation to make some changes, giving some a break because we are not bothered about who we play in the semi-finals," he said.
"South Africa have shown two different sides, more defensive against Iraq and more attacking against New Zealand. We believe they have some kind of magic, a real dynamic to their team.
"They are technically strong and have very powerful men in defence. Emotion is running high of course and they have their supporters behind them and for these reasons it will be a tough match."
