FREMANTLE star Caleb Serong says the Dockers can't wait to regain ruckman Sean Darcy for Sunday's crunch game against Melbourne, with the "centrepiece" of the team's midfield on track to return from concussion. 

Darcy missed Sunday's loss to Hawthorn after copping an accidental knee to the head against Richmond in round 17 but is on track to face the Demons at Optus Stadium if he can get through main training on Thursday.

While athletic sidekick Luke Jackson has impressed when given chances to lead the ruck this season, the midfielders missed Darcy's strength and big frame at stoppages against Hawthorn ruckman and former Docker Lloyd Meek and will welcome him back against the Demons this week.

"He's ticking every box so far with the concussion protocol. He's got to get through training and main training on Thursday and tick that off, but at this stage he's in a good space and ready to go," Serong said on Thursday as the Dockers launched their annual Starlight Purple Haze Game.

"It's amazing, everyone is trying to question the impact he has on the team. Early in the year when he was out, obviously Luke (Jackson) was playing some really good footy, but he's a barometer for us and he's such a big imposing character.

"He does a lot around the footy for us and gives us first look at a lot of the contests, and it's not often he's getting beaten in hit outs.

"So we can't wait to have him back and he's a massive centrepiece for us as a midfield group and as a team, so it's exciting."

Serong said key forward Josh Treacy had pulled up well from the Hawthorn game, which saw him spend stints in the ruck to support Jackson. Captain Alex Pearce is also on track to face the Demons after being held back for another week with a fractured left forearm. 

Sunday's clash against Melbourne at Optus Stadium shapes as a critical match in Fremantle's push to finish in the top four after the team squandered opportunities against the Hawks in a 13-point loss, with Serong keen for the Dockers to take control of their destiny in the run to finals. 

"It's a great opportunity with six games to go to really put our foot down and really assert ourselves on the competition and that's the opportunity we have right now," the midfielder said. 

"We can control how we go out there and perform against Melbourne and that's our focus at the moment, and I don't think it's lost on us the enormity of each game. To have something to play for every week, it's far more exciting than not. 

"We haven't been shy by saying that [top four] is what we want to get to. But the way we get there is not by wishing and hoping and praying, it's by going out there and doing actions and preparing each day like we have all year."

A group of Fremantle players were at Perth Children's Hospital on Monday to launch the 22nd Starlight Purple Haze Game, which aims to raise funds to brighten the lives of seriously ill children. 

Serong said the players drew inspiration from the children they visit, including this year's seven-year-old Starlight hero Imi, who was born with Fanconi Anaemia, an extremely rare genetic disease, which has seen her endure more than 40 procedures and multiple major brain surgeries. 

The Dockers will also wear a special themed jumper for the occasion. 

"We had a few guys speak up this morning in our meetings around the perspective you gain this week and how grateful we are to be in the position we are. The jumper is representative of that," Serong said.

"I think that is so powerful for everyone involved and it does give you a bit of a boost and extra motivation for the weekend."