NORTH Melbourne defender Erika O'Shea has been ruled out of the preliminary final against Melbourne as she continues to recover from an eye injury.

O'Shea was listed as a test this week, after accidentally running into the back of Courtney Wakefield's elbow three weeks ago in the round 10 clash with Richmond.

Kangaroos coach Darren Crocker for the first time detailed the extent of the nasty injury.

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"Erika's going okay. She's not up for selection this week, but she was very, very close, just trying to get the tick off from her specialist, and then our medical team will come together," Crocker said.

"But she's keen as mustard to get back out there, but not quite there yet. As I said, she won't be up for selection this week, but she wasn't too far away.

"From my understanding, she had some bleeding to the back of her eye, which had to correct itself with a little bit of assistance from eye drops, just so they could get into the back of the eye and make sure there was no damage, which there's no long-term damage.

"Now it's a matter of giving her time to get over that issue, not too much exertion at this stage, but hopefully we can build her out slowly, and hopefully she can train next week."

Crocker said Mia King (ribs) and Emma Kearney (knee) were right to play, with the skipper "finding a way" despite the joint not being at 100 per cent.

Melbourne has been North Melbourne's nemesis for much of its existence, holding an average winning margin of just 5.75 from its four wins, with the Roos taking the chocolates just once (in 2019), saluting by four points.

But the Roos appear to be hitting a steelier patch of form, pushing for the big three (Adelaide, Brisbane and Melbourne) to be expanded to four.

"I think [the gap is closing], but proof will be in the pudding on the weekend. Since I've come into this program (for the 2021 season), we've played Melbourne three times now, twice out at Casey and once at the 'G, earlier this season," Crocker said.

"I don't think the results have been more than six points, so we've had some really tight battles against them. At times, in every one of those games, each team has been able to gain a little bit of momentum, and I just feel that when Melbourne has gained momentum, they've been able to hurt us with their efficiency.

"They've been able to put some scoreboard pressure on, while we haven't been able to do the same to them to gain some (additional) momentum.

"So that'll be interesting. I feel we're better equipped, hopefully, forward of the ball in order to challenge Melbourne's defence, and hopefully that efficiency going forward will be better for us."

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O'Shea only trained lightly on the sidelines on Thursday night, completing skill work with teammates Vikki Wall and Alice O'Loughlin.

The forwards were on managed training loads and are expected to be named to face Melbourne, as is Sophie Abbatangelo, who trained fully despite suffering a pinky finger injury against Richmond.

Perri King ran laps with headphones as she continues to recover from a broken finger, while draftee Cassidy Mailer (leg bone stress) trained with the main group but is not available for selection.

The Roos cycled between gym and skill work to start their night, sharing the Arden Street oval with an extended VFLW squad, which has just started their pre-season training.

Goalkicking on the run was first on the agenda, before a switch to full-ground training, which was focused on ball movement to enter forward 50, changing lanes and hitting up short passes to targets in attack.

Numbers were boosted by train-on players, with even a few coaches pulling on the boots.

Further afield, the midfield core practiced its contest and stoppage work, including both slow and fast breaks from clearances.

What was potentially North Melbourne's last training session drew a crowd of 40-odd interested fans, as the session drifted to a close with 10 minutes of personalised craft work, as dictated by the players themselves.

Tahlia Randall focused on goalkicking, Jas Ferguson and Ellie Gavalas on general kicking and marking, while Ash Riddell and Jenna Bruton continued to toil away with stoppage work and bump bags.