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As the Seattle Seahawks prepare to host their arch-rivals on Sunday Night Football, the 12th Man needs to keep one thing in mind.

That 49ers fan you’re harassing could be a cop.

The Seahawks have announced that undercover officers will wear opposing team jerseys at home games, starting Sunday night. The move comes less than two weeks after the Seahawks began using non-uniformed police to monitor fan conduct at CenturyLink Field.

“We have great fans,” Seahawks president Peter McLoughlin said in a team-issued release. “Our goal is to ensure a safe environment for all in attendance, including visiting team fans.”

The 49ers have taken similar steps, starting during the 2011 playoffs. After Saints fans were harassed in the divisional round, officers outfitted with Giants jerseys attending the NFC title game.

Fans who are ejected from Seahawks home games are required to complete a four-hour online course, at a cost of $75, before being permitted to return.