The new man on the injury list is the Germany-based midfielder Rajko Tavcar.
The Nuremberg player hurt his knee tackling Dzoni Novak in training.
"His situation is not critical - he may be ready to train again within some days," said Kruh.
In addition, several players have colds and have had to be separated from the rest of the squad in the hope that the infection will not spread.
"We were forced to put the players with the colds together in double rooms," added Kruh.
Manager Katanec has refused to show any concern publicly and after finishing training on Friday morning, he went on his usual daily 10km jog.
Meanwhile, goalkeeper Marko Simeunovic said the players were keeping their focus on getting ready for the World Cup.
"We are doing our job here and are preparing ourselves for the matches," he said.
But he added that he had been delighted with the friendly reception of their Japanese hosts.