LONDON — Kayla Harrison is a self-described “huge” Celtics fan and admirer of coach Doc Rivers.

During a chance encounter with Rivers at the NBC broadcast headquarters Thursday night, the judo gold medalist from Marblehead, Mass., discovered that the admiration is mutual.

Rivers is here moonlighting as a studio analyst for NBC’s coverage of the basketball competition. He was preparing to do a segment when Harrison, who was scheduled for a later interview, walked in.

“I just get done hair and makeup, go in the green room, and there’s Doc Rivers, and I just yelled, ‘Ahhhh, it’s Doc!’ Harrison said, “and he comes over all excited and shakes my hand and says, ‘Is that a gold medal?’ He was so nice, so genuine. I was jumping up and down because I was so already excited.”

Rivers was so impressed that he asked to abbreviate his segment and have Harrison come on the set with him because, he said, “she’s a better story than anything we were going to talk about. I wanted to talk to her. I tell you, what an incredible person. It was so cool.’’

Harrison said she fell for the Celtics instantly when she moved to Massachusetts in 2007 as a 16-year-old. She attended a game at TD Garden with her fiancé as recently as April, sitting in the third row.

“People say all the time, ‘I’m a Celtics fan,’ and you’re like, ‘OK,’ because you find out maybe they don’t know who Paul [Pierce] is or something,’’ Rivers said. “But I can tell you, she is legit.’’

Rivers, who knew about Harrison’s back story as a sexual abuse survivor before he met her, is going to arrange for her to be honored at a Celtics game during the upcoming season.

“It would be great to get all the Boston-area Olympians on the floor,” Rivers said. “But I want to make special mention of Kayla, do something special.

“She’s a true survivor. I love that she talks about her story and wants it out and wants to help people.”

While Harrison knows plenty about Rivers’s sport, well, that isn’t mutual.

“I know nothing about judo,’’ Rivers said. “Actually, her manager was trying to explain it to me because I told him that I saw a match that morning and it lasted about 10 seconds. The person was flat on her back and I wasn’t sure what happened. But I told Kayla I needed her to teach all my bigs how to block out. She got a big kick out of that.”

CHAD FINN

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