Douglas was hospitalised after suffering a knock to the groin during Adelaide's practice match win against Greater Western Sydney last Friday.
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On return to Adelaide, he had surgery to stop persistent bleeding in the groin area, the Crows' football manager Phil Harper said on Monday.
"Medical advice on this points to a six-week recovery period," Harper said in a statement.
Crows to avoid the knife
"Richard will unfortunately miss the start of the season but as always, his health is our main priority. Importantly, he will make a full recovery."
Douglas, Adelaide's club champion in 2010 and runner-up in the award last year, joins forward Tom Lynch in missing the start of the looming season.
Lynch dislocated a shoulder against the Giants while utility Andy Otten is also in doubt for the Crows' March 20 season-opener in Geelong after jarring his reconstructed right knee against GWS.
