Boom Fremantle recruit Jesse Hogan and No.1 ruckman Aaron Sandilands are in doubt to return this AFL season after suffering further injury setbacks.
Hogan, 24, has been sidelined since injuring his right foot in a marking contest early in the clash against his former club Melbourne on June 22.
"I'm no expert in this area so we were planning and expecting for him to get up this week," coach Ross Lyon told reporters on Wednesday.
"But he ran on Monday and there was a bit of a hiccup there so we are behind the scenes working on that.
"It doesn't bode well that there has been a hiccup but it would be remiss of me to speculate."
After spending more than a year on the sidelines, the 36-year-old Sandilands made his return from a serious calf injury in the round-16 loss to West Coast, before sitting out last weekend's trip to Launceston to take on Hawthorn.
"If it is a calf strain, it would be significant rehabilitation and he'd have to get back late in the season," Lyon said.
"It would be at least three weeks I would imagine, if it's a strain."
The luckless Stephen Hill is also in doubt with quad soreness as the 13th-placed Dockers look to snap a four-game losing streak against a Sydney side sitting one spot below them on the ladder.
But in better news for the Dockers, promising defender Griffin Logue and key forward Cam McCarthy have agreed to new deals.
Logue has signed through until 2022, while McCarthy has a one-year extension for 2020.
Logue made his long-awaited AFL return in round 13 after more than 18 months out due to multiple injuries.
"Griffin has showed some elite athletic attributes that we think will hold him in really good stead going forward," said Dockers list manager Mark Micallef.
"We feel he can work really well with Joel Hamling and Alex Pearce as our key defensive pillars and we see really high growth with Griffin, so we thought a three-year extension with him was a great result for the club."
Australian Associated Press