The 71-year-old German said Saturday's opponents were fast, determined and tactically astute and told his players that Korean panthers would pounce if their concentration lapsed in their Group B encounter at a wind-swept and chilly Port Elizabeth.
"In 1962 I travelled through Asia and played local teams and won 6-0, 7-0 and even more. That was long ago and since then the Asian teams have caught up massively," Rehhagel said.
"They have wonderful ways to move and we really can't imitate that as Europeans. They run like panthers - they're like big cats. They're very clever when it comes to tactics, they know what football's all about.
"I've told my guys that if you think for a fraction of a second that you can afford not to pay attention, you'll be badly sanctioned," he added.
Rehhagel, who led Greece to a shock Euro 2004 triumph, evaded questions about his own team's tactics, complaining of having "already said too much" and darting out of the news conference after less than 10 minutes of largely tangential comments.
The Greek players are keen to forget their miserable World Cup past having lost all their games and failing to score a single goal in their sole appearance in 1994.
Captain Giorgos Karagounis, a veteran of the Euro 2004 campaign, was a little more forthcoming than his coach and said ambition had got the team through to the finals and they would show it again against a slick and speedy South Korean side.
He played down talk that Greece, who typically play with one striker, were not attack-minded, but admitted clean sheets were the team's priority over goals.
"We go forward and we try to score, we wouldn't have achieved much without scoring," Karagounis said.
"Of course, our main feature is our compact defence and our main target is not to concede. We will start by trying to not concede a goal."
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