The 57-year-old took Japan to the 2006 World Cup but they struggled in Germany, managing to pick up just a single point in a goalless draw with Croatia as they finished bottom of their group.

The East Asians lost their opening game against Australia at that tournament and Zico believes failure to get off to a good start once again in South Africa could see them ultimately heading home early.

"The key match for Japan is the first game against Cameroon," the former Brazil midfielder told Press Association Sport.

"If they can win this game it will make things easier because they are in a very hard group."

Japan open their Group E campaign against Cameroon on June 14 before playing Holland and Denmark.