Central defender Marinko Galic, who has a thigh problem, will also miss training until the weekend.
Slovenia coach Srecko Katanec has eased the tempo of his team's preparations because of jet lag caused by the long journey to Mimasaka.
Katanec praised the hospitality of the local people on Honshu Island.
"Although we are scheduled to play all our World Cup matches in Korea, our Japanese hosts in Mimasaka should get a lot of credit for our possible success," he said.
Local people have even planted a linden tree - the national tree of Slovenia - in Mimasaka in honour of their guests.