Toure had been in red-hot form with Norwich City, scoring five goals in the opening seven games of the English Championship season.
That included firing home a terrific opener against Bolton before injuring his shoulder in a tussle.
"Mo Toure will be out for months and he will need surgery. So that's a bad one," City coach Philippe Clement told The Pink Un website at a Norwich community event on Tuesday evening.
Toure had already been ruled out of Australia's upcoming matches against Brazil in Townsville on Friday night and Brisbane next Tuesday, with Nishan Velupillay called up instead.
But the South Australian is now set to miss a significant chunk of his domestic season.
While the full timeline on Toure's recovery has yet to be confirmed, the Asian Cup, which starts on January 7, is just three-and-a-half months away.
Even if Toure is able to return before then, his build-up would be restricted.
It leaves Nestory Irankunda and Tete Yengi as the Socceroos main options in the No.9 for the games against Brazil, and potentially the Asian Cup.
Irankunda remains in contact with best mate Toure ahead of Friday night's match in Townsville, but could only hope the striker would be back "soon".
"We've had a few conversations, you know. Just wishing him all the best in his recovery," Irankunda said on Wednesday.
"It's a huge, huge loss for us, but he'll be back soon.
"He (Popovic) makes the calls at the end of the day, and I'm always ready to play.
"Wherever I play, it doesn't really matter to me, as long as I'm playing in the team and trying to help the team win games and succeed."
Toure has scored 16 goals and tallied four assists in 21 games in all competitions since joining Norwich in January.
The 22-year-old entered the World Cup with high hopes but failed to fire.
Toure started Australia's first two World Cup games against Turkey and the United States before coach Tony Popovic chose to use Irankunda ahead of him for games against Paraguay and Egypt.
Young defender Lucas Herrington could only wish Toure a speedy recovery.
"He was killing it in the Championship, so it's sad to see," Herrington said.
"But he's got a good head on his shoulders, so he'll get back to it."
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