That fan is 85-year-old Carolyn Purdy, a resident at the Atria Senior Living facility.
She was tight-lipped about any possible relation to 49ers quarterback Brock Purdy.
"Maybe, maybe not. I'm not saying," she said.
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Purdy has been an avid 49ers fan for more than 50 years.
First getting hooked thanks to her late husband.
"He would explain it all to me and he would answer all the questions. And we got the season's tickets at good old Candlestick," Purdy said.
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Purdy says she's seen almost every game since 1972.
The includes being a spectator at the 49ers 1985 Super Bowl win.
For Purdy, cheering the Niners on is about more than just watching a sports game.
"You forget about everything else. All the stuff that's going on. You just lose yourself in the game," she said.
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Over the years, Purdy and her husband collected rooms full of 49ers merchandise.
"All the paraphernalia, the jerseys, the pennants," Purdy said.
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Prudy says she had to part with most of her collectibles when she moved into her current home.
But that hasn't stopped her from donning some of the items she's kept ahead of Sunday's big game, says Atria's executive director, Freddie Fullon Jr.
"She's been wearing jerseys, tee shirts, jackets. She has the original gold jacket. Things that are bedazzled," said Freddie Fullon Jr.
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With the game now just hours away, Carolyn says she'll eagerly try to pass the time.
But when game time rolls around on Sunday, she's got a message for Kansas City fans.
"Send them home crying? Yeah, they'll be crying. They'll be feeling sad."