Erik Karlsson was a marvel in the first round of the playoffs, and yet he wasn't even playing at full health.

Following the Ottawa Senators' dramatic Game 6 overtime win over the Boston Bruins on Sunday - to send them to the second round - Karlsson admitted he played the series with two hairline fractures in his left heel, according to ESPN.com's Joe McDonald.

Karlsson explained that the injury occurred when he blocked a shot in a March 28 game against the Philadelphia Flyers. That ailment forced the 26-year-old to miss five games.

Fortunately for the Senators, it doesn't appear as though the injury should impact Karlsson much longer.

"I've been playing on shots (injections) and by Thursday it should be back to normal," Karlsson said.

Despite the ailment, Karlsson has been his usual offensive self, leading all defensemen in the playoffs with six points (all assists).