Tennis' ATP Cup has so far raised more than $21,000 for bushfire victims, while Australia's rugby sevens players are the latest sports stars to pledge donations to help with $500 for each try they score.
With 216 aces served up in Sydney, Brisbane and Perth on opening day of the ATP tournament, $21,600 will go towards the Red Cross' fire relief fund.
However organisers have set a target of more than $150,000, with the expectation at least 1500 aces will be served by singles and doubles players across the 10-day event.
Team USA's John Isner so far leads the list of big hitters, racking up 33 aces despite going down to Norway's Casper Ruud in three sets at RAC Arena in Perth.
Second is Australia's Nick Kyrgios who belted 20 aces in his cup-opening defeat of Germany's Jan-Lennard Struff in Brisbane.
Each winner also saw Kyrgios donate $200 from his own pocket for bushfire victims, while teammates John Millman and Akex de Minaur have also offered personal pledges.
Australia's men's and women's sevens teams have meanwhile promised $500 to the Red Cross every time they touch down at Rugby Australia's annual Sydney 7s tournament next month.
Wallabies winger Reece Hodge is also auctioning off a signed Australian jersey along with his match-worn boots from the recent Rugby World Cup via his Instagram account.
Tennis Australia will launch a "Rally for Relief" exhibition at Rod Laver Arena in Melbourne on January 15 and donate proceeds from a Jessica Mauboy concert on January 19 to the Red Cross appeal.
TA chief executive and Australian Open tournament director Craig Tiley says $1m will be granted to communities to rebuild tennis facilities.
"I'm glad the tennis world has taken the initiative and hopefully we can do whatever we can," Kyrgios said on Friday.
"We all earn a lot of money and at this stage a bottle of water can save a life."
NBA-bound LaMelo Ball, who plays for Illawarra Hawks in the NBL, has pledged to donate one month of his salary to help victims of the devastating fires.
Big Bash League captains, Brisbane Heat's Chris Lynn and Melbourne Stars' Glenn Maxwell as well as Hurricanes batsman D'Arcy Short, have pledged $250 for each six they hit in the competition.
Former Australian baseballer Simone Wearne has kickstarted a campaign to donate for every home run hit in the Australian softball championships.
Australia's cricketers will auction off signed shirts from the Boxing Day Test while Cricket Australia will throw open the gates to firefighters during two SCG one-dayers against New Zealand in March.
Melbourne A-League clubs - Victory, City and Western United - will donate $2 from every ticket sold at their matches this weekend.