The 27-year-old suffered a left-shoulder dislocation in pre-season training last week and the club said he was undergoing arthroscopic surgery on Tuesday.

Acton - who last year forced his way into the starting line-up late in the season at the expense of Lawrence Thomas - has targeted a return towards the end of the season.

"It's unfortunate to lose a talent like Matt from the group for a sustained period," said Victory coach Marco Kurz.

"The outcome is disappointing for everyone.

"He is a popular member of the squad and will continue to contribute to the group in any way that he can.

"We wish him a speedy recovery and look forward to having him back at full fitness as soon as possible."

Victory's A-League season starts on October 12 in a derby against Melbourne City.

Thomas is now seemingly assured of starting as goalkeeper although he is also returning from injury and was training separately from the main group earlier this month as part of his rehab.