Adelaide forward Kurt Tippett has been withdrawn from the side to play Fremantle tomorrow in a blow for the high-flying Crows.
Tippett had been expected to return after a three-week stint on the sidelines suffering the effects of concussion.
Crows captain Nathan Van Berlo had told a media conference the 202cm forward trained well today, he was ruled out within the hour.
Tippett will be replaced by young forward Lewis Johnston.
The news is a major boost for the Dockers, who lost All-Australian contender Luke McPharlin to a one-week ban after failing to clear him of a rough conduct charge at the tribunal on Tuesday.
Fan favourite Alex Silvagni was named to replace McPharlin tomorrow, with the Dockers preferring to play three tall defenders against the potent Crows forward line boasting the likes of Taylor Walker (192cm) and Josh Jenkins (197cm).
After bursting onto the scene with 15 games in 2010, Silvagni has managed just 12 of a possible 40 since, with a run of frustrating injuries limiting his availability and hindering his form.
His last match for Fremantle was in round 14, then he was dropped after conceding three goals to out-of-form Collingwood forward Chris Dawes.
Consistent form for Claremont - including a role in the Foxtel Cup grand final victory - has seen him beat out form Peel backman Peter Faulks and veteran Docker Antoni Grover for the spot.
Dockers coach Ross Lyon stressed the need for Fremantle to put in an even effort across the field to cut off Adelaide's forward thrusts.
"Adelaide rank No.1 for goals from marks in the AFL. That tells you a bit about how they like to score," Lyon said on Thursday.
"They're a really big challenge.
"But we're going to rely on pressure up the field. Why we were able to defend well last week is about pressure around the ball, and we need to bring that again.
"We've got faith in our systems but it's all underpinned by effort.
"You talk about technicalities and mechanics but, if you don't bring work ethic and put effort in, it's hard to bring things to life, so we know it starts with that."
Fremantle have won their past five games to move within 0.8 per cent of eighth-placed Essendon, while second-placed Adelaide (14-4) need to keep winning to shore up a top-two berth.