SYDNEY coach John Longmire has urged for speculation surrounding Patty McCartin to cool as the key defender deals with another concussion that is threatening his career.

Speaking on Wednesday afternoon, Longmire revealed that 19-year-old midfielder Corey Warner, the brother of Swans star Chad, will debut on Friday night against Richmond.

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But it's the future of key defender McCartin that remains the number one issue around the Swans after he was subbed out against Port Adelaide following a seemingly innocuous head knock on the SCG turf.

Longmire said the 26-year-old is "feeling okay" while he rests and recovers but is still dealing with some concussion symptoms from the incident.

McCartin played all but one game last season in an excellent campaign, but missed three years prior to that as he battled the affects of repeated head knocks.

"I was obviously not far away from it, I was concerned," Longmire said.

"We'll get the facts, Patty's obviously involved and a key part of this. There's an expert team that's been involved all the way along for the last three years and will continue to be involved and give Patty the specialist advice.

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"Hopefully there's not a lot of speculation about the what ifs because that's not healthy for him either."

Longmire said there have been no conversations at all with McCartin about his playing future.

"We haven't had those discussions and the advice we've had is to just focus on his recovery - that's the most important thing for him to be putting his energy into right here and now," he said.

"To be thinking beyond that is just a step too far.

"The thinking of everyone at the footy club, his family and Patty is just making sure he recovers and starts feeling okay.

"We're not putting any timeframe on it."

The Swans will go into Friday night's clash against Richmond at Adelaide Oval without either of the McCartin brothers, with Tom also out for a week due to concussion protocols.

That would seemingly open the door for former Bomber Aaron Francis or 2019 draftee Will Gould to make their Swans debuts, but Longmire revealed both failed to complete training on the weekend as they battle minor hamstring and foot injuries respectively.

That leaves the Swans light on in options in the key defensive post and potentially reliant on Dane Rampe to play on a taller opponent, which he's done with aplomb throughout his career.

"Obviously Tom Lynch is out and we're not sure what Richmond will do," Longmire said.

"We've got the ability for guys to play on taller players. Nick Blakey has some height on him and can play on taller guys if required. We feel like we'll be okay in that regard as long as there’s pressure up the ground."

Pick 40 in the 2021 draft, Warner will make his Swans AFL bow alongside superstar brother Chad in a Gather Round debut.

"That's exciting for him to get a taste and run out there with his brother Chad," Longmire said.

"He's got a great mix of speed and endurance (and) he got bigger and stronger over the summer. He's certainly put on some size and that's fitted in well with his running capacity.

"He's put in a solid body of work that warrants his inclusion this week."

The Swans will also be without legendary spearhead Lance Franklin, with Longmire confirming Hayden McLean will come back into the side in place of the eight-time All-Australian.

"Lance was a little bit sore on the inside of his knee. We'll see how he is for next week, the main thing is for him to get himself right over the next few days. Hopefully if he bounces back okay then he'll be able to do some training next week," Longmire said.

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