GEELONG has suffered a huge blow on the eve of the 2020 NAB AFLW season, losing All-Australian defender Meg McDonald to a broken finger.

McDonald, who also took out Geelong's best and fairest last year, is currently looking at missing the first four weeks of the season.

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The 28-year-old underwent surgery on Friday after suffering the injury at training the previous night.

"There is no doubt it’s disappointing for Meg to sustain an injury so close to the beginning of the season," Geelong head of women's footy Simone Bellears said.

"But we are confident she will do all she can to return to the field as soon as possible."

Geelong's Meg McDonald produced an All-Australian season after moving to defence

The intercept defender and general of the backline will not be easily replaced, with 19-year-olds Georgia Clarke and Becky Webster possible options, having played down back as juniors.

The pair have been training as a forward and midfielder respectively this summer.

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Meanwhile, father-daughter recruit Millie Brown was in a moonboot at the club's season launch on Friday night and will have scans on Saturday.

In terms of other injuries, the Cats are confident classy trio Nina Morrison (ACL), Olivia Purcell (shoulder) and skipper Melissa Hickey (knee) are on track to take on Fremantle in round one, despite none of them participating in practice matches.

Defender Anna Teague (concussion) is still a few weeks away.