Co-hosts Australia suffered a major setback Thursday with captain and star striker Sam Kerr ruled out of at least their first two Women's World Cup games with a calf injury.

The Chelsea forward is the country's all-time leading scorer and the face of the tournament, but will miss the Matildas' opening match against Ireland later Thursday and the clash with Nigeria next week.

"Unfortunately I sustained a calf injury yesterday in training," she said in a statement. "I wanted to share this with everyone so there is no distraction from what we came here to achieve.

"Of course I would have loved to have been out there tonight, but I can't wait to be a part of this amazing journey which starts now," added the 29-year-old.

Arsenal defender Steph Catley will take over as captain against Ireland, with Mary Fowler starting up front in place of Kerr.

The team said their medical team will "re-assess her following our second group-stage match".

Kerr made her Australia debut aged just 15 and has gone on to become one of the best players in women's football, with her profile soaring to new heights since moving to Chelsea in 2020.

She has been shortlisted for the women's Ballon d'Or and nominated for the Best FIFA Women's Player consistently since 2017.

In 2019, Kerr became the first Australian, man or woman, to score a hat-trick at a World Cup, but winning a major trophy with her country has eluded her.