Richmond veteran Chris Newman is set to miss up to six weeks due to a calf strain.
Former captain Newman suffered the injury in the fourth quarter of his AFL side's five-point defeat to Geelong.
Scans on Monday confirmed the 31-year-old had a medial calf strain, but the club is optimistic he will only be out for four to six weeks.
"This is the first soft-tissue injury Chris has had in his 12-year career," Richmond's elite performance manager Peter Burge said on Richmond's website.
"He's a good healer and is optimistic the injury won't keep him out of action for too long."
The loss of Brett Deledio, who was reported for striking and can accept a one-match ban, and Newman would hurt the Tigers' chances of getting their season back on track.
Richmond have the bye in round eight, but then face must-win matches against Melbourne and Greater Western Sydney.
The Tigers, boosted by the inclusion of Alex Rance and Deledio on Sunday, finally started to resemble the side that posted 15 wins in 2013.
But having lost to the Cats, they remain in 13th spot on the ladder thanks to a 2-5 record.
Key forward Jack Riewoldt said the belief was back after an impressive showing against Geelong.
"Although we didn't get the four points, we definitely improved our performance," Riewoldt said on Monday.
"A few guys got some confidence back so that's a positive."
