The Sydney Swans have shown their support for star forward Lance Franklin as he continues treatment for a mental health condition.

The Swans, who released a statement on Tuesday explaining Franklin's condition, have rallied around the key forward, who is now "in the best area for him personally".

Football manager Tom Harley said the club was doing everything possible to support Franklin and its first priority was looking after the 28-year-old's health.

"Lance has been open with the club about his condition and while we consider it a private medical matter, he is aware he has our full support," Harley said.

"The timeframe on his return is unclear at this stage. He will certainly miss this week’s match and we will continue to monitor his condition."

Swans coach John Longmire, who addressed the AFL Commission three years ago about mental health issues in the AFL, said he had spoken to Franklin, who had the best possible care and support.

"It's a shock to a lot of the boys … we can just support him as a player group and as a footy club, and that's what we'll do," Longmire said.

"We're right behind him, we support him fully, and footy's the last thing on our minds in regards to his health.

"All the players have spoken about it and we're fully behind him."

Longmire said Franklin's decision to share his mental health battle with teammates, club staff and the public would help him understand how common such struggles were.

He said the club was very confident the star forward would emerge successfully.

"He's now talking about it, which is a big step forward," Longmire said.

"It does not discriminate as far as an 18-year-old kid who comes from interstate and is struggling with a lot of different issues, or one of the very best players in the game.

"A lot of people are able to deal with it and be very successful, and we're very confident that will be the case with Lance."

Co-captain Jarryd McVeigh spoke on behalf of the players on Tuesday and said Franklin's battle was not something they had known about.

"You see the players every day and some players do struggle every now and then," he said. 

"It's not something you really do know about until he's put his hand up and said, 'I do have an issue'. Then we talk about it as a group and support him.

"That's all we can do."

Franklin joined the Swans as a restricted free agent at the end of 2013 and signed a nine-year, multi-million dollar deal that runs until the end of the 2022 season.

He missed four matches from rounds 17 to 21 with a back injury and has been rusty in the past two weeks, being substituted in round 22 and kicking one goal in round 23.

The former Hawthorn star will be joined on the sidelines against Fremantle by key midfielder Kieren Jack (knee) and Luke Parker (ankle) and defender Nick Smith (hamstring).