The NBA All-Star Luka Dončić scored 25 points for Slovenia, one fewer than Zoran Dragić, while Vlatko Čančar contributed 16.
Dončič said Japan had a great team who play fast and added that while the Slovenian team played well, they still have room for improvement when it comes to defense.
In its first Olympic appearance ever, the Slovenian team on Monday defeated the World Cup runners-up Argentina. Their next match is scheduled to get underway on Sunday when they face Spain in Group B.
The quarter-finals will be played next Tuesday, August 3rd, the semis in exactly a week on August 5th, and the finals next Saturday, August 7th.