In what she described as a “win for the ladies” the American, who has won 21 Grand Slam singles titles, chased down the man who she claimed “grabbed her phone and swiftly left”.
She said: “Not thinking I reacted (hence the superwoman photo), I jumped up, weaved my way in and out of the cosy restaurant (leaping over a chair or two) and chased him down.”
Williams said she was “too fast” for the man and was “upon him in a flash”.
She added: “In the most menacing, yet calm, no-nonsense voice I could muster, I kindly asked him if he ‘accidentally’ took the wrong phone.”
“He stumbled on his words, probably not expecting this to happen. Eventually he said: ‘Gosh, you know what, I did! It was so confusing in there. I must have grabbed the wrong phone.'”
Williams, who won every Grand Slam singles title except the US Open this year, said she received a “standing ovation” from her fellow diners at the restaurant.