The Tampa Bay Lightning are keeping quiet about the extent of the injury Victor Hedman suffered in Thursday's game against the Dallas Stars.

Hedman left the game in the second period after taking a hit from Jamie Benn, the defenseman's head slamming into the glass.

Head coach Jon Cooper said Friday that Hedman's feeling better, according to the Tampa Tribune's Erik Erlendsson. But Cooper offered no official injury status, only ruling out the 24-year-old from Saturday's home game against the Buffalo Sabres.

Cooper's optimistic that Hedman, who may have suffered a concussion, will be back sooner rather than later.

Tampa Bay could be facing a very depleted blue-line corps on Saturday, with Hedman out and Nikita Nesterov facing a possible suspension after hitting Stars forward Curtis McKenzie from behind. Nesterov will have a hearing with the league at 4:30 p.m. ET on Friday.

The Lightning will officially call up defenseman Slater Koekkoek from Syracuse of the AHL on Friday evening, Erlendsson added.