The play seemed innocent enough.

Separated by only two inches in stature, Ottawa’s Erik Karlsson and Pittsburgh’s Matt Cooke went to the corner boards of Consol Energy Center battling for the puck. Cooke has about 25 pounds on the reigning Norris Trophy winner and they got tangled up.

Losing his balance, Cooke’s left skate came off the ice. Then it came back down ... on Karlsson’s Achilles.

Season over.

Ottawa general manager Bryan Murray said 70 percent of Karlsson’s tendon was cut on the play, and recovery time will be about four months from his Thursday surgery.

“That’s hockey,” Flyers captain Claude Giroux said. “Stuff like that’s gonna happen. It’s too bad for Ottawa because he’s one of the best players in the league. He’s a dynamic player — not just for Ottawa, but for the NHL. It’s not good news.”