"We are a small country of just five million people, England are a much bigger country and a much more powerful football nation," said Danish head coach.
"If I believed we were the favorites I would say so, but we are not," Olsen added.
While he admits that the Danes are underdogs, Olsen says history shows that a upset victory against England isn't impossible.
David Beckham leads the English against Denmark on Saturday.(CP Photo)
The 52-year-old coach was a member of the Danish side in 1983 that recorded the only previous win over England in 14 attempts. He would gladly settle for a repeat of that 1-0 score in Niigata.
"I have told the players that the team I played in beat England and so can they," he said.
Olsen has two major injury worries to think about. Jon Dahl Tomasson, who has scored four goals in the tournament so far -- is still nursing a groin strain picked up in the match against France while combative midfielder Stig Tofting has a sore left foot.
"We will decide tomorrow (Saturday) whether they are fit or not," Olsen added. Both players did some light training away from the main group, but it was widely expected both would start."
Going back six more years to the 1986 World Cup, each country had reached the quarter-finals once and the round of 16 once. However, England gains an edge having been to the semifinals at Italy '90. Denmark failing to qualify for the finals that year.
England manager Sven-Goran Eriksson said his side would need to control the possession if they are to progress to the quarter-finals against either Brazil or Belgium.
"You have to keep the ball and at times be very quick, if they give you the chance," he said.
You must be aggressive and not give them time to have any shape or to keep the ball -- they are very good at that. You have to play very, very good football."
The Swede knows plenty about Denmark and predicted that the likes of Jesper Gronkjaer and Dennis Rommedahl would be a threat on the wings.
"I think it's going to be a quick game, both teams are very quick to attack if they get the chance, so I think there will be chances to score goals for both teams," added Eriksson.
While his Olsen cast the Danes as underdogs, Eriksson said it would be an even contest.
"I don't know who's the favorite," he said.
"I saw all three of Denmark's games and they did very well, they deserved to win the group, they played good football."
Eriksson said he was not worried that his team had yet to score a goal in open play at the finals and predicted that Michael Owen was ready to break out.
"I'm not worried," he said of Owen, who is without a goal after scoring twice at the finals four years ago.
"I think he is playing better and better - in the last game he was very lively. He will score."
England will again be without Canadian Owen Hargreaves. The Calgary-native was injured in England's 1-0 victory against Argentina,
Eriksson said he will likely stick with the same eleven players that started the 0-0 draw against Nigeria.
"There will not be big revolutions," Eriksson added. "Absolutely not."
