The Flyers were forced to play the final two periods of Saturday's 5-2 loss to Colorado shorthanded at forward after James van Riemsdyk left the game when he was hit by a clearing attempt in the knee and did not return to the game.
JVR was the team's big free agent acquisition, and now the Flyers will have to go through a good chunk of the season without him.
The Flyers announced that van Riemsdyk will be out for approximately five-to-six weeks with a lower-body injury.
JVR had an assist in the team's season opener on Thursday and was held without a point through the first period of Saturday's game when he left. He is coming off a 36-goal season with Toronto.
At practice on Monday, Jordan Weal was placed in JVR's spot on the third line at left wing and Oskar Lindblom was taking his spot on the second power-play unit.
The Flyers open up the schedule at home on Tuesday against the San Jose Sharks. Game time is at 7 p.m.