Tom McCartin speaks with the trainers during the round eight match between Sydney and GWS on May 4, 2024. Picture: AFL Photos

SYDNEY defender Tom McCartin is "feeling really good" after sustaining a concussion during Saturday's derby against Greater Western Sydney, coach John Longmire says.

McCartin, who has been in the midst of an excellent start to the season down back, was subbed out in the second quarter after a head-high hit from Callum Brown that saw the Giant suspended for three games.

McCartin missed nine games last year after complications from a concussion in round four against Port Adelaide, raising fears that he may have an extended period out again.

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His coach, though, has allayed those for now.

"He's feeling really good, which is a real positive. He wasn't knocked out during the actual incident so that's a relief for everyone and he can recall everything that happened, and he's pulled up well," Longmire said.

The 24-year-old will miss Friday night's clash in Perth against Fremantle through concussion protocols, but it's unclear at this stage if he'll return for the Friday night clash the week after against Carlton, where his presence would be invaluable against Charlie Curnow and Harry McKay.

"His recollection is really clear and he can remember everything. That's all we can go on for the moment. He's obviously in the protocols and we'll follow that but he's feeling okay," Longmire said.

Aaron Francis will be the favourite to replace McCartin for the trip west if the Swans go for a like-for-like replacement while former Docker Joel Hamling, who played as a forward in the VFL last week, will also be in the mix.

Aaron Francis spoils Sam Day's mark during round 22, 2023. Picture: AFL Photos

Luke Parker's chances of a first AFL game for the season will only be strengthened after 37 disposals and a goal amid the rarity of his second VFL game in a row, following a pre-season broken arm.

While Longmire will ponder how he finds a place for the three-time club champion in a team that is top of the ladder, he also queried as to whether it's time for a send-off rule in the AFL after the McCartin incident.

"Is it a reasonable approach to consider that down the track? Maybe. Only the real clear incidents, maybe it's worth a consideration but I'm not jumping up and down about it. It wouldn't be to punish the player it's just to even it up," he said.

"These incidents do happen in football but is there a way we can even it up on match day? That's a consideration for the experts down the track."

McCartin's absence will be sorely felt when the Swans play away to the sixth-placed Dockers this week, but the impact of Dane Rampe, who kept Toby Greene goalless on his return from injury last week, has helped reinforce the key back stocks.

Dane Rampe (left) and Oliver Florent celebrate a win during round eight, 2024. Picture: AFL Photos

"He's a good player he has been for quite a while," Longmire said of Rampe.

"He was terrific on the weekend, he took an extra week probably (to recover); he was tossing up playing the week before. In hindsight it was the right decision he came out and played a really good game."

The midfield battle on Friday night promises to be a salivating one with Isaac Heeney, Errol Gulden and Chad Warner currently occupying three of the top four score involvement places in the competition.

They'll be going head-to-head with the in-form Caleb Serong, Andrew Brayshaw and Hayden Young, who have helped the Dockers amass the second most clearances across the competition this season.

"Freo is the second-best defence in the competition and the best clearance team by a long, long way, and they're playing on their home deck," Longmire said.

"It's a game we're really looking forward to and taking on a really good Fremantle team, their midfield has been outstanding it'll be a good battle in there."