Hayley Raso will miss Australia's crunch Women's Asian Cup clash against South Korea with concussion in a blow that could potentially open the door for Mary Fowler to start in their crucial Group A clash.
Raso was struck twice on the head after coming off the bench in Thursday's 4-0 win over Iran on the Gold Coast.
The 31-year-old did not train with the Matildas squad on Saturday.
Raso started Australia's tournament opener against the Philippines but ceded her starting spot to Fowler against Iran.
The winger will be forced to sit out Sunday's vital clash in Sydney which will determine the winner of the group and, providing she is cleared to play, could return in next week's quarter-final.
"We're just following the medical protocols in terms of a light concussion," said Australia coach Joe Montemurro.
"From my own personal perspective it is something we don't mess around with.
"We just want to make sure that everything's right and she's progressing really well but she won't be available for tomorrow (Sunday).
"We just follow the seven-day protocol at the moment and we will assess from there but all signs are positive but she is not out for the tournament."
Raso's hopes of being given more training time over the next week will hinge on Sunday's result at Stadium Australia.
Owing to their inferior goal difference in contrast to the unbeaten Koreans, Montemurro's side need to win to finish top of their group.
Should they win on Sunday, the Matildas will stay in Sydney for the remainder of the tournament and get an extra day's rest ahead of a Saturday, March 14 quarter-final.
A draw or loss would add to the travel load with the runner-up in Group A on a tighter schedule and forced to travel to Perth for a Friday, March 13 quarter-final.
"The travel is a big one because this is such a tight tournament," Montemurro said.
"Having just one pre-match training session leading into tomorrow's game is very tight.
"Obviously the advantage is (less) travel. We're in the quarter-finals, that's the most important thing but whatever comes our way we'll cherish it and take it from there."
Montemurro, meanwhile, hinted goalkeeper Mackenzie Arnold and midfielder Kyra Cooney-Cross could both be in line for their first tournament minutes against South Korea.
Arnold has been sidelined with a calf complaint while Cooney-Cross has also not featured for Australia at the tournament.
Cooney-Cross took a leave of absence from club side Arsenal following her mother's cancer diagnosis earlier this year and has had limited gametime with her Women's Super League club.
"She (Cooney-Cross) will be in the squad tomorrow and all going well we'll try to integrate in the right way," Montemurro said.
"Kyra's smiling and back in the squad and we're all happy to see her back."
