Speaking on the eve of his second Group H match, Hitzfeld said Chile, who reached the World Cup finals ahead of Argentina in South American qualifying, will be favourites in Monday's clash, with strong individual players and attacking flair.
"They are very strong when it comes to running, to physical presence, they are also very strong in one-to-ones, very quick in breakaway attacks, very direct play," the German coach said on Sunday.
"Chile is a team that's extremely dangerous, they're also very aggressive when it comes to forward play, more aggressive than Spain even, so we've got to reinforce our defence work, we have to be more concentrated in order not to concede a goal."
Both teams are in the unlikely position of joint group leaders after the Swiss beat the Spaniards 1-0 and Chile defeated Honduras by the same score in their first win at a World Cup in nearly half a century.
Chile's last win in the competition was in the 3rd/4th place playoff as hosts in 1962. They had since qualified for the World Cup four times but failed to win any group matches.
Hitzfeld refused to say if he would stick with the same lineup against the South American team.
"It's only a possibility. But we might as well have a lineup with two or three forwards to really go for the attack and put pressure on Chile. That's what we might attempt," he said.
Both he and his players were careful not to let the win over Spain go to their heads, he said.
"All players have realised just how sensational the win against Spain was ... we cannot take it for granted to just simply blow away Chile with our hands down. It will be very hard work," he said.
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