Williams’ gesture was meant as a show of support for the staggering number of animals that have been killed or harmed by the fires, according to the United States Tennis Association. Experts estimate that more than one billion animals have been killed during the crisis, which has destroyed around 16 million acres of land.
Photos of Williams' nails began surfacing online after her match, with fans pointing out that the ring finger on both of her hands had been painted to resemble a koala. Her other nails were decorated in her famously creative mid-match style.
Williams, who has the second most Grand Slam titles in women’s tennis history, has been active in raising awareness about Australia’s bushfires for weeks now.
Earlier this month, she announced she would join tennis stars Roger Federer and Rafa Nadal in playing a charity match to raise money for relief efforts. Just a few days later, Williams donated her $43,000 prize from a tournament in Auckland, New Zealand, to the cause.
"I am heartbroken over the devastation of the wildfires in Australia. With the loss of over 500 million animals and many people left without their homes, we need to act now to help in whatever way we can," Williams wrote in an Instagram post at the time. "I have been going to Australia for over 20 years so this devastation is hitting me particularly hard."