Sharapova admitted she was taken aback when her bill at a Melbourne cafe arrived together with the waiter's smartphone and a request for a photo, along with an autograph.
Sharapova, who was relaxing ahead of next week's Australian Open, duly took a picture -- not of herself, but of a man sitting nearby.
"I actually took a picture of the guy next to me. True story," she told journalists on Saturday.
The brush-off suggests Sharapova is in no mood for frivolity as she embarks on the season's first Grand Slam, following a four-month lay-off with a shoulder injury.
Sharapova, who has long struggled with her right shoulder and had surgery in 2008, said she was delighted to be in Australia after missing last year's US Open.
"I'm happy to be back playing a Grand Slam. I missed the last one at the end of last year," she said. "I'm happy to get myself back in form and really start well here."
Sharapova, a four-time Grand Slam winner who reached last year's semi-finals, added: "You obviously have to lower your expectations a little bit and be a bit realistic about maybe the first few matches.
"You have to grind, work through them, hope to get better as the tournament goes on."
Australian Open: Maria Sharapova snubs waiter's 'selfie' request
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