Richmond have confirmed star defender Dylan Grimes will undergo surgery on a hampered hamstring, likely meaning the Tigers will require a deep finals finish to see their co-captain back on the field this year.
The club confirmed on Tuesday that Grimes would miss the coming weeks of action due to his latest setback, a major blow to Richmond's rearguard as they press for a top-eight finish.
Speaking to media on Thursday, Tigers coach Damien Hardwick admitted the club will likely be relying on a finals finish to give Grimes a chance to return this year.
"That'll rule him out for the regular season," Hardwick said.
"Depending on how we go, (surgery) will give him his best chance (to get back this year)."
The Tigers will again remain without superstar Dustin Martin, who is sidelined for the coming weeks as he continues to battle a hamstring issue of his own, with the club hopeful the three-time Norm Smith Medal will be available for their Round 23 clash with Essendon.
Saturday night's trip to Adelaide Oval to face the Power stands as a must-win match for Hardwick's side, who currently sit outside the top eight by two premiership points.
A win could see them move into the finals frame, before upcoming matches against the Hawks and then Bombers.
The Tigers will confirm their lineup for Round 21 at 6:20pm (AEDT) on Thursday night.