She knocked his socks off — and then put them on.

Morgan Riddle wore a special good luck charm last year to boyfriend Taylor Fritz’s matches — his crisp white size large Nike socks, she told The Post.

“Just because at the beginning of the week, I had no clean socks, so I just put his on before his first match, and then he won,” she said.

And so she decided to wear them throughout the Indian Wells Masters in California in March 2022.

“I got a little superstitious about it, and then he ended up winning the tournament,” she said.

Riddle, 26, will be cheering on Fritz, 25, as he competes at the US Open, which begins on Aug. 28 in Queens — but will keep his socks at home this time.

“Taylor doesn’t really have any superstitions except taking a cold shower before his match. I don’t want to put pressure on him,” she said of her beau, who is ranked No. 9 in the world by the Association of Tennis Professionals.

The pair met on on the elite dating app Raya in May 2020 — and at first, the Minnesota native played hard to get after connecting with Fritz, who is from California and has a net worth is $3 million.

“The pandemic had just started. I was just like, ‘I don’t really want to jump into anything,’ but he was pretty persistent,” she said.

At the time, Riddle wasn’t aware he was a pro athlete, she insisted.

“I had seen a photo on his profile of him playing tennis, but I just assumed that it was a college team,” she said.

Now the blonde beauty, who is the first significant other of a tennis player to be sponsored by clothing brands, travels with Fritz 35 weeks a year and has made a career as an influencer, partnering with labels like Ralph Lauren and FRWD.

“Prior to me posting content, no WAGs [wives and girlfriends] have been dressed by brands for matches, but we have so much TV time … that it honestly just makes sense,” she said.

Her foray into influencing began Jan. 2022 when she was with Fritz at the Australian Open. On the same exact day she quit her job as a media director at a nonprofit, she posted two outfit options on TikTok — and asked users to decide which one she should wear to the tournament.

“I had a couple hours to kill before Taylor’s first round match … I posted that first one … and it had a million [views] overnight,” she said.

She also gets her share of criticism on social media — which she lets bounce off her.

“Luckily in general I have very thick skin,” she said. “A really common hate comment that I get is, ‘She’s just unemployed and follows her boyfriend around the world. Get a job.'”

Riddle, who comes from a long line of dairy farmers, dreamed of coming to the Big Apple after watching the ABC series “Ugly Betty,” which didn’t “romanticize” the daily grind of the city.

“It’s basically about this girl from Queens who just grinds her butt off to make it at a magazine and I just loved the idea of that,” she said. “I know [for] a lot of people it’s ‘Sex in the City’ or ‘Gossip Girl’ that draws them to New York.”

She attended Wagner College on Staten Island and graduated in 2019 with a degree in English literature — and said living in New York back then helped her acclimate to her newfound role as a player’s boyfriend.

“If you’re a partner on tour, you’re spending an excessive amount of time by yourself. And I think going to college in New York kind of fostered this in me that I don’t have any problem eating by myself … taking public transportation by myself,” she said. “I can do anything alone and be perfectly content.”