"Japan's group is very tough," Antic told Reuters before Wednesday's friendly against the Japanese in Osaka. "The culture of the game makes Holland and Denmark very tough opponents.
"Cameroon have (Inter Milan striker Samuel) Eto'o who can score goals anytime. Japan will need to be very organised. That will be the key for them to get through that group."
Japan coach Takeshi Okada has refused to backtrack after declaring his target in South Africa as a place in the last four despite being drawn in a daunting Group E and his side having never won a World Cup match on foreign soil.
Antic said his side's chances of reaching the last 16 were better with Serbia in Group D against Germany, Ghana and Australia in their first major tournament as an independent nation, which begins on June 11.
They played at the 2006 World Cup in Germany as Serbia & Montenegro, making a swift exit after losing all three of their group games before the country's break-up.
"All four teams have the potential to go through for sure," he said of Group D. "But we have great belief in our ability. To coach the team at its first World Cup as 'Serbia' is an honour.
"I have confidence we will do very, very good things at the World Cup. We're not going to South Africa to be tourists."
Antic's team for Wednesday's World Cup warm-up is a relatively inexperienced one made up of domestic players, as is Japan's.
Antic has opted to leave the job of coaching the side to his understudy Radovan Curcic but demanded the youngsters seize their chance by beating Japan.
"The players will be on show," said Antic. "They must step up and show me they can do a job for Serbia at the World Cup."
Antic said the race for Serbia's World Cup places was still wide open, stumping the Japanese interpreter by smiling: "I don't take my shoes off until I go in the water."
