UPDATED: Following the team's loss to Pittsburgh, Flyers GM Paul Holmgren said that Timonen will be re-evaluated on Friday on his lower-body injury.
The Flyers currently have three players who began the season who are dealing with injuries.
Both Scott Hartnell and Vincent Lecavalier left the Flyers-Coyotes game on Oct. 11 and have missed the last three games with an upper-body and lower-body injury respectively.
On Oct. 12, Flyers GM Paul Holmgren expected Hartnell to be out of action for 2-4 weeks, while Lecavalier would miss a week of action.
With regards to Timonen, Holmgren announced after the second period of play in last night's loss to the Penguins that he suffered a lower-body injury and would not return to the game.
He appeared in 19 shifts through the first two periods of play and posted 13 minutes of ice time, before leaving the game.
He has played in all seven games so far this season, going scoreless and recording 21:43 of ice time to lead all defensemen and second-most on the team, behind only Claude Giroux (22:04).
Counting defensemen Chris Pronger and Marc-Andre Bourdon, the Flyers currently stand at 22 man-games lost through the first eight games of 2013-14.