TORONTO — NHL executive Colin Campbell said Thursday that linesman Tony Sericolo erred in not whistling the play dead for offsides before Danny Briere’s first goal in Game 1 of the Penguins-Flyers series.

“There’s no other way to explain it but a missed call,” the NHL’s senior executive vice president of hockey operations told The Canadian Press. “We’re as upset as Pittsburgh, almost. It’s a mistake.”

Briere scored Philadelphia’s first goal on Wednesday night after being sent in on a breakaway by teammate Brayden Schenn. The long pass came immediately after a neutral-zone turnover and replays showed Briere was a couple feet offside.

The play started a big comeback for the Flyers, who erased a three-goal deficit and beat Pittsburgh 4-3 in overtime. However, the Penguins refused to use it as an excuse for their collapse.