France coach Claude Bergeaud was left to rue his side's 77-61 defeat in their opening qualifier in Slovenia.
Beno Udrih top scored for Slovenia with 18 points while Marko Tusek poured in 12 for Les Bleus who have been deprived of the services of NBA star Tony Parker for their qualifying matches.
|Marko Tusek - 12 points and 11 rebounds|
Slovenia edged the first quarter 20-19 but were hammered 24-12 in the second as the hosts piled up the baskets.
Honours were even in the third period which was shared 16-16 before Les Bleus lost further ground in the final quarter which they lost 17-14.
Claude Marquis managed 17 points for France while Florent Pietrus contributed 11 in a match attended by 2500 spectators in Celje.
Bergeaud told L'Equipe: "Slovenia have some very strong players.
"As for the scoreline there is no need to worry - it illustrates the real difference between the teams.
"We can only hope that Slovenia continue playing like this until their last match. If they don't they could spoil the party without wanting to.
"In other words if they beat Czech Republic that can cause us enormous problems at the end."