Elina Svitolina said she will donate her prize money from WTA tournaments to Ukraine's military and to help with humanitarian efforts following Russia's invasion of her country last week.
The world No. 15 told Eurosport her family and friends in Ukraine were defending the country and that she wanted to help.
"Really until the very last moment we did not believe that this war would actually start and then everything just happened at night ... Everyone is terrified, everyone is heartbroken," she said.