Hearts boss Jim Jefferies has conceded that Andrew Driver will almost certainly require surgery to cure a persistent knee problem.
Driver has managed only 11 games this season as a number of injuries have blighted his campaign.
"The big blow is that Andrew has battered on [with the injury] as long as possible and it has affected him," said Jefferies.
"He might go in for an operation before Saturday's game but we'll see."
The Tynecastle boss also hopes Andy Webster will recover from a groin strain in time for Saturday's trip to face Rangers at Ibrox.
The ex-Rangers defender was taken off at half-time during the 3-3 draw with Motherwell and subsequently missed the weekend draw with Kilmarnock.
"There has been a slight improvement with Webster so we will keep our fingers crossed," commented Jefferies.
While Webster may feature at Ibrox on Saturday, the match will probably come too soon for team-mate Lee Wallace, who is struggling to shake off an ankle injury.
A victory for Hearts in Saturday's match would clinch third place in the league for the Tynecastle outfit, although Rangers need three points to keep pace with Celtic in the race for the league championship title.
However, Jefferies sees no reason why his team can not come away from Govan with a positive result given previous encounters this season.
"They have all been tight matches. There's not been a lot between the teams so I wouldn't rule us out.
"I know when Rangers are this close to going for the title, they become a little bit more difficult because there is a will there to keep the pressure on Celtic."