Pittsburgh Penguins defenseman Kris Letang is officially week to week with a lower-body injury suffered Saturday versus the Detroit Red Wings, head coach Mike Sullivan announced Monday.

It's believed he suffered a left knee injury while being tangled up with Thomas Vanek.

Letang exited the ice in distress, unable to bear weight on his leg. He took one short shift a little later on, but did not return after that.

Staying healthy has been a challenge for Letang throughout his career. He's made 70-plus starts once in the last five 82-game campaigns, and has wound up on injured reserve twice already this season.

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