National team manager Akira Nishino expects to agonize over his World Cup selections right up until he names his 23-man squad on Thursday but hopes Wednesday's friendly match against Ghana will provide some answers.

"I don't need to tell the players that they are fighting for their survival," Nishino told reporters at Nissan Stadium on Tuesday, one day before he takes charge of the team for the first time after replacing fired predecessor Vahid Halilhodzic last month.

"There are more than 23 players here and I can only include a set number of them on the list. I have to think about the balance. I've been thinking about how to get the players into their best condition, and we will see what happens in tomorrow's game. After that, we have to expect that there might be some injuries. I think the questions will continue."