Scotland and Bath rugby star Russell sidelined by 'significant injury'
Russell, the Scotland co-captain, was forced off with a suspected groin problem early in Bath's 21-15 defeat away to southwest English rivals Exeter on April 6.
Bath centre Cameron Redpath, also a Scottish international, left the pitch in the second half of the same match with an ankle injury.
"Finn suffered a significant groin injury in the Investec Champions Cup round-of-16 tie against Exeter Chiefs," Bath's head of medical, Rory Murray, said in a statement. "His availability will be assessed weekly."
Murray had a similar fitness assessment for Redpath, saying he had "sustained significant ankle ligament damage" and would also be assessed weekly.
Flanker Ted Hill is being monitored for a chest injury and remains doubtful for Bath's English Premiership match against the Chiefs on Saturday.
Bath are second in the Premiership table with four games to play in the regular season.
The top four at the end of the campaign will contest the title-deciding play-offs, culminating with a final in June.