Collingwood has been dealt a hammer blow less than a month out from the AFLW finals series after scans confirm star midfielder Brittany Bonnici had sustained an ACL tear.

The helmeted midfielder took to Instagram to announce the news after sustaining the injury within the first quarter of Collingwood's win over the Bulldogs on Sunday.

"Bloody footy hey," Bonnici typed on Monday afternoon.

Unfortunately scans have confirmed what I had hoped so badly they would not, a torn ACL will see me sent to the sidelines for a while but every setback provides opportunity, I’m sure I’ll find exactly that. Some hard work ahead but I’m ready for the challenge.

Thanks to everyone who’s reached out and got in touch. Can’t put into words how much the support means. Onwards and upwards from here."

While the 24-year-old will now join fellow Collingwood star Brianna Davey on the sidelines with an identical knee injury, Bonnici signed off by expressing her pride in the Pies' season-altering win at Victoria Park.

THE BIG QUESTION: Why are AFLW players more prone to ACL injuries?

"Side note - How good were the @collingwoodaflw girls yesterday! My god I’m one proud lady right now!"

Collingwood will now be left the tackle their remaining fixtures against league leaders Adelaide and fellow finals aspirants Gold Coast ahead of the finals in autumn.

Bonnici's output this season had well and truly cemented her status as one of the elite ball-winners within the Women's competition, averaging 19 disposals and 3.3 marks in each appearance this summer.

The St Kilda Sharks product became an inaugural member of Collingwood's W team after joining the club with the 27th pick of the 2016 AFLW Draft.