According to France manager Didier Deschamps, Arsenal's Laurent Koscielny has a minor calf strain that will keep him out of tomorrow's international match.
As you can probably guess after looking at a map, this match was not part of France's World Cup qualifying campaign. Australia is not part of FIFA; having already qualified for the World Cup out of Asia, they scheduled a friendly with France to coincide with this international break. As you might guess, even with a very minor injury, it's not worth risking a player's health for a friendly, under pretty much any circumstances.
So we will probably have to wait at least until France's final qualifier on Tuesday against Finland to see how injured Koscielny is, and possibly until he returns to Arsenal next week. It could be worse than it sounds, but for now I assume this is a national team manager looking out for a player's long-term interests and nothing more.
EDIT: Never mind waiting.