Olympic tennis champion Belinda Bencic and Tunisian Ons Jabeur have tested positive for COVID-19.
Both said they were fully vaccinated and were experiencing strong symptoms.
Jabeur recently defeated Bencic in the Mubadala World Tennis Championship final.
The news comes after Rafael Nadal announced on Monday he had also tested positive.
"While the timing is not ideal - as I was in the final stages of my preparations for the Australian Open swing - I will make my way to Australia as soon as I am cleared and past the isolation period," Bencic said on Twitter.
Jabeur said she was isolating in Tunisia.
The Australian Open begins on January 17.
Will be back soon! 🙏 pic.twitter.com/iJCktGQ1VT— Ons Jabeur (@Ons_Jabeur) December 21, 2021