Cates (personal) won't play Thursday versus the Canadiens.
Cates scored what turned out to be the game-winning goal in Tuesday's win against Florida.
Cates (foot) will be activated off injured reserve and return to the lineup Monday against the Blues.
Cates (foot) was placed on injured reserve Tuesday, per the NHL media site.
Cates is expected to be out of action for six-to-eight weeks because of a lower-body injury.
Cates scored a goal on four shots in Tuesday's 3-2 loss to the Golden Knights.
Cates signed a two-year, $5.25 million contract with Philadelphia on Monday, Elliotte Friedman of Sportsnet reports.
Cates picked up a goal and an assist in Saturday's 5-4 overtime loss to Carolina.
Cates had a goal and an assist in Saturday's 4-0 win over the Jets.
Cates scored a goal on three shots in the Flyers' 3-2 overtime loss to the Wild on Thursday.