Harding, the backup to Niklas Backstrom, tore both his anterior cruciate ligament and medial collateral ligament during the first period Friday night in an exhibition loss at St. Louis. Blues forward Brad Boyes accidentally fell on Harding's leg.
Harding, who played 25 games last season for the Wild, will have surgery after swelling in the knee goes down. Wild general manager Chuck Fletcher would not rule out the possibility of Harding returning this season.
With Harding out, Anton Khudobin will start Sunday night at Montreal. The 24-year-old Khudobin spent most of last season with Houston of the American Hockey League, but did play in two games for Minnesota.
Fletcher said Saturday he would evaluate all options -- including making a move for another goalie -- during the rest of the preseason.