Karlsson (undisclosed) is unfit to play Thursday in Boston, Dean Brown of TSN 1200 reports.

EDGE Analysis

The two-time Norris Trophy winner provided some heroics in his last two games, tallying a goal and an assist Monday when he wasn't expected to play and potting another goal Tuesday, but seems to have suffered some kind of setback. Karlsson is Ottawa's best player and one of the best players in the entire league, so the Sens chances to clinch a playoff spot Thursday have certainly been dealt a blow. In his absence, Jyrki Jokipakka will step in to the Ottawa lineup.