Although Greece will likely count themselves lucky to avoid the likes of tournament favourites Brazil, Spain and Argentina, Fernando Santos' men were drawn into the potentially tricky and unpredictable Group C.
Matches against Colombia and Ivory Coast come either side of the meeting with Japan, who Dellas feels represent Greece's biggest threat.
Dellas, a key part of Greece's UEFA Euro 2004 triumph in Portugal, is wary of the damage that the likes of Shinji Kagawa, Keisuke Honda and Hiroshi Kiyotake can inflict.
The AEK Athens coach told thetoc.gr: "We need to rely on our strengths as a team, (particularly) good defensive work as a team. The key will be to not accept easy goals.
"We should have a clear mind if we are to meet our goals and build for phases ahead. If we go by the logic that we are better than what we are, we will have a problem.
"In a World Cup you have to not only deal with European teams, who have common characteristics. There are teams that have different football cultures.
"Ivory Coast is a young team with very good physical skills, speed and physicality. What I think is that they are lacking concentration in their game, like the other African teams.
"We are dealing with Japan, which for me is the most dangerous team. It is a disciplined team.
"We also believe that Colombia, like all teams in Latin America, have unpredictability in them, which is dangerous.
"When you're dealing with three different cultures, we must keep to our own strengths and hit their weaknesses. If you were to choose a favourite I would say Japan a little more than the rest."
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