Argentina finished an unprecedented third at the last World Cup, having launched their successful campaign with a shock 17-12 victory over hosts France.
The Pumas went on to beat Ireland and Scotland to reach the semi-finals, where their run was halted by eventual champions South Africa.
Argentina claimed the bronze medal with a second victory over Les Bleus - and Contepomi revealed the Pumas will be adopting the same "anything is possible" attitude at this World Cup.
"I think that they are better than us and that they will be better than us after the game as well - but in this 80 minutes anything can happen," said Contepomi, a former Toulon team-mate of Jonny Wilkinson.
"We were also in this situation in the last World Cup. We always feel we need to play those 80 minutes, you always start at zero-zero. I'm not saying we will beat them, but we can."
Argentina's exploits at the last World Cup earned them an invitation to join the All Blacks, Australia and New Zealand in a a new Four Nations tournament, to be launched next year.
The Pumas have slipped to ninth in the world rankings but they are the seeded team in Pool B and have beaten group rivals England and Scotland plus France and Italy since the 2007 World Cup.
England are certainly not under-estimating the Pumas.
"When you play a team like Argentina in the first game, it's a massive challenge," said England manager Martin Johnson.
"They're a very difficult team to play. If people call us favourites or not, we've got to go and win that battle."
The form guide suggests that the team finishing second in the group will face tournament favourites New Zealand in the quarter-finals, which is something the Pumas will be keen to avoid.
And that only strengthens their desire to make a fast start against England under the roof of the remarkable new Otago Stadium.
"It's too much to think of a possible clash with New Zealand as the All Blacks are the big favourites for this tournament, and everyone will try to avoid them if they can," said Contepomi.
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