FREMANTLE ruckman Sean Darcy has hit a hurdle in his preparation for round one after suffering a minor knee injury at training this week.

Darcy, who was enjoying a standout summer under the Dockers' new fitness regime, will need to wear a brace for between two and four weeks.

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The injury puts him in doubt for the AAMI Community Series and could open the door for big man Lloyd Meek, who is yet to debut in his three seasons.

The Dockers said the extent of Darcy's injury would be reassessed when he is out of the brace. 

Sean Darcy kicks the ball at a Dockers training session in January. Picture: fremantlefc.com.au

"Scans have shown that Sean has damaged his arcuate ligament in his left knee," football manager Peter Bell said.

"The current advice is he will need to wear a knee brace for the next two to four weeks.

"This means Sean will miss a number of weeks of pre-season training and the injury will be reassessed once he is out of the knee brace." 

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Darcy this week spoke about his improved fitness under new high-performance manager Phil Merriman.

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The 22-year-old, who has an unfortunate pre-season injury history, said he was intent on getting through the next stage of the summer without interruption. 

"I feel like I'm covering the ground a lot better. I'm not as tired in training, I'm thinking a lot more clearly, and I'm making the right decisions," Darcy said on Wednesday. 

"There's obviously a lot more work to go, which is good, but I'm feeling a lot better.

"We're not doing the same running that we used to do last year, so it's been a really good change.

"I feel like I'm running really well … I feel a lot fitter."