Stoinis left the field two balls into his seventh over and had a scan in the evening with a Cricket Australia spokesman saying it showed a "low grade side strain" which will be "managed accordingly." The quick turnaround between matches - the second game is on Sunday - would seem to make it unlikely he will be available for it.
Stoinis, who made a first-ball duck in Australia's huge total of 374, has a history with side injuries having also suffered one at the 2019 World Cup.
Green, the Western Australia allrounder, who has also been named in the Test squad, was picked largely on the back of his first-class record, with his List A numbers being more modest.
"Fingers crossed [Stoinis] is okay, if he's not someone has to come in and probably someone who has to bowl overs so perhaps Cameron," Steven Smith said. "He's started really well in the Shield season, he's a bright talent.
"I faced him for a couple of balls in the nets this afternoon before the game, it's the first time I've seen him bowl and he bowls a heavy ball. He looks an impressive talent and if he gets the opportunity hopefully he can take it with both hands."
Ahead of the series, Australia coach Justin Langer had said Green would play in the ODI side only if he was able to be a full part of the bowling attack. And though Green returned to action with the ball for the first time in a year during the last two rounds of the Sheffield Shield, his role was limited to four-over spells.
Another option Australia have in their squad is Moises Henriques, who was recalled for the first time since 2017, and is also a like-for-like replacement for Stoinis. Other names would be Sean Abbott as a pace-bowling allrounder or Ashton Agar which would provide another frontline spinner.
Andrew McGlashan is a deputy editor at ESPNcricinfo