The Penguins on Monday morning placed defenseman Kris Letang on injured reserve and recalled two players from their farm team in Wilkes-Barre/Scranton: forward Jake Guentzel and defenseman Chad Ruhwedel.
Letang sustained what appeared to be a lower-body injury on Saturday in Detroit, when he got tangled with Thomas Vanek in the corner and left the ice grabbing his left knee.
The injury occurred at 3:21 of the first period. Letang took one more shift, lasting all of 17 seconds, before calling it a night.
The fact that he's on IR means the injury will keep him out the rest of the week, at minimum, and could be more serious.