ADELAIDE ruckman Sam Jacobs will miss at least another week with knee soreness.
The Crows have ruled out the 31-year-old for their round five clash with Gold Coast on Easter Sunday at Adelaide Oval.
Jacobs trained on Tuesday morning, but wasn't able to complete enough work to be given the green light to return after being sidelined for the past two games.
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The 198-game veteran hasn't played since taking a knock to his right knee in the round two win against Sydney at the SCG.
The Crows don't have a timeframe for when Jacobs will return, with Reilly O'Brien taking his place in the meantime.
"Sam's knee had shown encouraging signs of improvement over the last two weeks," Crows science and medical services coordinator Steve Saunders told afc.com.au.
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"Unfortunately, Sam is still presenting with meniscal symptoms that have prevented multi-directional and dynamic training progressions despite other improvements in function.
"It is a complex meniscal problem with acute and longstanding or chronic pathologies involved.
"Sam will be re-evaluated by club specialists over the next 48 hours and we will provide updates to his management plan as the club's medical team works through all options available."
The extended absence of Jacobs is another blow to the under-performing Crows (1-3) as they aim to turn their season around against the Suns.
It will be O'Brien's fifth game of his career and his longest consecutive stretch after his previous two appearances came in round 20-21, 2016.
Crows midfielder Matt Crouch was confident O'Brien would be able to step up to the challenge.
"Rob's shown he can play at the level," Crouch said.
"He's a different ruckman to Sauce, but he can definitely play at the level.
"It's not great news for Sauce, not really sure where it sits at the moment for him, but it's good for Rob to get an opportunity to play."