San Francisco police plan on sending officers undercover in gear of the 49ers' opponents in Sunday's game at Candlestick Park as part of an effort to maintain safety in the stadium.
Some officers will be wearing Detroit's blue and silver jerseys while others will be wearing 49ers colors as they stay on alert for criminal activity and unruly fans during the game.
Police will also be monitoring scalping and sales of counterfeit tickets or merchandise before the game.
Police Chief Greg Suhr used a similar tactic last season, as well as for baseball games between the San Francisco Giants and rival Los Angeles Dodgers earlier this year.
The 49ers won their season opener 30-22 at Green Bay last weekend and play their first home game of the season at 5:20 p.m. Sunday.
The team made it all the way to the NFC Championship last season before falling in overtime to the eventual Super Bowl champion New York Giants.