Hearts winger Andrew Driver is out for six weeks and striker Calum Elliot is facing a lengthy spell on the sidelines.
Star winger Driver is suffering from tendinitis in his foot and will not be back in action until the middle of September.
Elliot could be forced to undergo surgery as he battles to overcome a heel injury and manager Csaba Laszlo admitted the outlook was bleak.
He told the club's official website: "The biggest problem is Elliot and his heel.
"He maybe needs an operation or an injection to get the inflammation out so Elliot is out for a long time."
England Under-21 international Driver had pledged his immediate future to Tynecastle after being linked with a summer exit, and his absence will hit Hearts hard in the opening weeks of the new SPL season.
Laszlo, who has also confirmed his interest in Charlton striker Izale McLeod, said: "Andrew Driver is out for six weeks and this is not good.
"We don't like to push him into the wrong situation."
Admitting his interest in McLeod, which was initially revealed by skysports.com, the Hearts boss insisted the striker was one of a number of players under consideration.
He added: "We know this player but there are two or three other targets, too.
"We have two and a half weeks before the season starts and we are trying to do something."