Ivica Osim hopes an old friend will not turn into a foe by putting a dent in his side's Asian Cup preparations as Japan take on international new boys Montenegro in their Kirin Cup opener on Friday.

The Bosnian coach has admitted he has little information on his opponents, but has been friends with Montenegro coach Zoran Filipovic since his own time in charge of the former Yugoslavia and knows the Montenegrins will need no extra motivation to mark their acceptance as FIFA's 208th member association with victory at Shizuoka Stadium Ecopa.

"The only knowledge I have of the current Montenegro team is the video footage I watched of the only other game they have played this year," said Osim, referring to the Montenegrins' 2-1 win against Hungary in March.

"I am certain they will be highly motivated to win on this occasion. That said, it doesn't mean they will be any more motivated than we are. Don't forget we are representing a nation too," he said.