Serena Williams challenged two guys at Dolores Park to an impromptu tennis match

Serena Williams of the US poses with the championship trophy after her victory against Venus Williams of the US in the women's singles final on day 13 of the Australian Open tennis tournament in Melbourne on January 29, 2017. less Serena Williams of the US poses with the championship trophy after her victory against Venus Williams of the US in the women's singles final on day 13 of the Australian Open tennis tournament in Melbourne on ... more Image 1 of / 82 Caption Close Serena Williams challenged two guys at Dolores Park to an impromptu tennis match 1 / 82 Back to Gallery

Tennis icon Serena Williams was taking a leisurely stroll Sunday night around San Francisco's Mission District with her fiancé, Reddit co-founder Alexis Ohanian, when she saw something that caught her attention: two guys playing tennis at Dolores Park.

At first she thought she might challenge them to a match anonymously, but being one of the greatest athletes alive, she was promptly recognized.

"Oh my goodness," one person on the court says. "Is this for real?"

Williams appeared to indeed to be for real, even though she didn't have her preferred tennis shoes — just a pair of furry boots. It seems she didn't play a full set, though; TMZ notes that the footwear may have held her back.

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"Don't try this at home!" she told her Snapchat followers.

Watch the whole thing here, put together by USA Today's Alysha Tsuji:

Serena played tennis in boots with these 2 guys she saw on a court while she was out on a walk last night. IMAGINE. pic.twitter.com/kWXrTE73M9 — Alysha Tsuji (@AlyshaTsuji) February 27, 2017

Williams has found herself in San Francisco quite a bit lately, ever since she started to date San Francisco-based Ohanian. The pair announced their engagement — how else? — via a Reddit post in late December 2016.