Hearts have seen their injury problems continue after Ben Garuccio was ruled out for the rest of 2019.
The 23-year-old Australian left-back – who joined Hearts on a three-year deal last summer – suffered a knee injury in training and joins fellow full-backs Demetri Mitchell and Michael Smith on the sidelines.
Manager Craig Levein said: "We got a bit of bad news on Wednesday. Ben Garuccio has torn his cruciate in training. So he will be out for 10 months or so.
"His foot got caught in the turf and twisted, just a complete accident."
The latest blow leaves Marcus Godinho and Jamie Brandon as the only recognised full-backs in Levein's first-team squad, although Jake Mulraney and Bobby Burns have both played as wing-backs.
Mitchell is not expected back this season after undergoing knee surgery while Smith faces a race against time to return from a thigh problem in time to face Inverness in the William Hill Scottish Cup semi-finals on April 13.
Levein said: "Michael Smith is improving but he's not ready to play yet."
Meanwhile, Levein has dismissed suggestions he will be looking over his shoulder at a resurgent Hibernian, whose head coach Paul Heckingbottom revealed his players were targeting Hearts after moving two points off their Edinburgh rivals.
Levein, whose team host Aberdeen this weekend, said: "I'm more concerned with Saturday's match and getting three points.
"We can all make noises but it's where you end up after the final game of the seasons that's important and there's still a long way to go."
Meanwhile, Levein declared an end to hostilities with Dons boss Derek McInnes ahead of Saturday's game.
The Hearts boss reacted angrily to his counterpart's comments that he was "always looking for penalties" in December and the pair traded jibes over an extended period.
When asked about their disagreement, Levein said: "If I gave you the list of the people I have had a disagreement with....
"Derek and I are fine."