(CNN)Australian tennis stars are supporting victims of Australia's bushfires by donating money for every ace they hit at upcoming tournaments.
Nick Kyrgios made the initial pledge of $200 (140 USD) for each ace on Thursday, before Alex de Minaur, who will star alongside the world No. 30 at the upcoming ATP Cup, replied with his own offer.
"I like this I will go $250 (175 USD) per ace, just because I don't think I'll be hitting as many aces as you mate," de Minaur wrote on Twitter.
Their teammate John Millman also chipped in: "I'm not at your level boys but I want to get involved," he wrote. "$100 (70 USD) for an ace over the Australian summer. #servingupsomehelp"
World No. 99 Samantha Stosur matched Kyrgios' offer of $200, urging people to "join me in any way you can."
Kyrgios also saw his call for a charity tournament to raise funds for bushfire victims answered by Tennis Australia this week.
"C'mon @TennisAustralia surely we can do a pre @AustralianOpen exho (exhibition) to raise funds for those affected by the fires?" he said on Wednesday.