First-choice ruckman Toby Nankervis appears set to spend at least a month on the sidelines due to a knee injury, in a blow to Richmond's AFL premiership defence.
Nankervis was hurt at the opening centre bounce in the Tigers' 28-point win over Adelaide last weekend, but played out the game.
Follow-up scans confirmed a sprained posterior cruciate ligament.
"(Nankervis) is going to require a couple of weeks out of the game, just for it to glue up and for him to do a little bit of strength work around that and get his stability back to normal," Richmond physical performance manager Peter Burge said.
"We will have a better idea in the next week or two about his return to play, but at this stage, it is probably a medium-term injury."
Nankervis joins fellow premiership players David Astbury (achilles), Tom Lynch (knee), Kane Lambert (calf) and Ivan Soldo (knee) on the injury list.
Former All-Australian midfielder Shane Edwards (ankle) is likely to return in Saturday night's 'Dreamtime in the West' clash with Essendon at Optus Stadium.
"Shane has had a great last seven days," Burge said.
"He had a session last Friday in Melbourne and then again Sunday, which were fantastic.
"He came up (to Sydney) on Sunday and he has done a training session today (Tuesday), which has gone really well.
"We are in a position Thursday where he might be training with the group, and if that is the case, we think he will be probable for this weekend."
Richmond are stationed in a temporary base in Sydney and are due to fly to Perth on Friday.
Their schedule beyond Saturday's Essendon clash remains unknown as the AFL rejigs its fixture because of Melbourne's COVID-19 outbreak.
