Naomi Osaka sent a cheeky message to her sister while signing the Australian Open camera following her big win over Serena Williams

• Naomi Osaka took down Serena Williams in straight sets at the Australian Open on Thursday.
• After their semifinal match, the 23-year-old signed the camera as is tournament tradition.
• She wrote a message to her sister, Mari, on the lens: "stop sending werid images in the groupchat!"

Naomi Osaka was unrelenting as she dismantled Serena Williams during their Australian Open semifinal bout on Thursday.

But once the match was over and she'd cleanly secured her 6-3, 6-4 victory, the three-time Grand Slam champion was all smiles and even had some jokes for the viewers back home.

After a lighthearted on-court interview, Osaka walked across the court to sign the tournament's camera lens, a tradition for match winners at the Australian Open. But players often add doodles and messages alongside their autograph, and in typical 23-year-old fashion, Osaka used the opportunity to take a jab at her older sister, Mari.

The Japanese international didn't hesitate as she approached the camera and wrote in blue marker, "Mari stop sending werid images in the groupchat!" She smirked slightly as she added her signature beneath the message, then walked away without a second glance.

Typo notwithstanding - got 'er!

It's not the first time Osaka has added a little something extra while signing the camera. Following her quarterfinal victory over Hsieh Su-wei, the 2019 Australian Open winner attempted to draw a cat on the lens but was wholly unimpressed with her 'ugly' result.

Now that she's had her fun, Osaka will undoubtedly get serious about shifting her focus to Saturday's final. She'll face Karolína Muchová or Jennifer Brady - neither of whom has made a Grand Slam final - on Saturday to pursue her second Australian Open title.

And if all goes her way in this weekend's championship match, perhaps she'll celebrate her fourth career Grand Slam victory with one final drawing or funny message before heading out from Down Under.