Captain Sam Kerr declared herself available on Saturday for Australia's must-win clash with Olympic champions Canada in a major boost for the Women's World Cup co-hosts.
It came as European champions England sweated on the fitness of key midfielder Keira Walsh after she was stretchered off in their win over Denmark with what looked like a serious knee injury.
Prolific Chelsea striker Kerr, the face of the World Cup in Australia and New Zealand, suffered a calf injury on the eve of the tournament and missed the Matildas' first two games.
The Australians, who were one of the favourites to win the title, squeezed past Ireland 1-0 thanks to a penalty to open their campaign but were then stunned 3-2 by Nigeria.
That left their World Cup in serious peril and underlined just how much they missed their talismanic goalscorer.
With the critical encounter against Canada looming on Monday, the 29-year-old fronted the media in Brisbane to say: "I am going to be there, I am going to be ready."
But Kerr declined to say how much of a part she will play in the clash in Melbourne.
"I would love to tell you guys everything but you know being in sport a long time that that's a massive thing that the opposition wants to know," Kerr said.
"It is going to go down to the wire. I am definitely going to be available but how we decide to use that is not to be given to the opposition."
- Walsh fears -
The 26-year-old Barcelona midfielder Walsh appeared to suffer a serious knee injury against Denmark on Friday.
There has been a spate of knee injuries in women's football and England were already missing captain Leah Williamson and Euro 2022 Golden Boot winner Beth Mead for that reason.
Coach Sarina Wiegman said after seeing her side win 1-0 to stand on the cusp of the knockout rounds that it was too early to say how badly Walsh was hurt.
"Of course I'm concerned because she could not walk off the pitch," said Wiegman, whose strongly fancied side won thanks to a sixth-minute stunner by Lauren James.
"But we don't know yet (how bad the injury is) so we can't make any assumptions."
There was also concern over another World Cup star.
Colombia's talented 18-year-old attacker Linda Caicedo went down in training on Thursday clutching her chest and may not play against Germany on Sunday.
Coach Nelson Abadia called it "an episode of tiredness, a bit of stress over her debut in a senior World Cup".
"It was just an episode and she is ok now," he added. "Linda has overcome the event.
"Whether she will play, we have 24 hours or a bit more to decide."
- France-Brazil clash -
Back on the pitch there were three matches on Saturday as the teams do battle to reach the knockout rounds.
Sweden face Italy at 0730 GMT before a heavyweight meeting between France and Brazil at 1000 GMT.
France, who were among the teams touted as a threat to holders the United States before the World Cup, need victory after being held 0-0 by Jamaica.
But they meet a Brazil side flying high following a classy 4-0 thumping of Panama.
Jamaica play Panama in the last game of the day, starting at 1230 GMT.
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