Philippe Clement says Danilo will be missing until at least the winter break and could require surgery after a tackle in Wednesday's win over Hearts.
The Brazilian striker, 24, has been a mainstay in the team since Clement arrived in October but is now expected to be out of action until at least the new year.
Tom Lawrence, who was forced off early on during Wednesday's match, is also expected to be out until the winter break.
Danilo's injury leaves Clement's options light up top. Cyriel Dessers, 29, has struggled to make an impact since arriving at the club in the summer, Kemar Roofe has battled with injury issues in the past two seasons and Sam Lammers has largely played at No.10.
"Tom will be out until the winter break. Danilo will be out also. So that's not so good," Clement said looking ahead to Saturday's visit of Dundee.
Asked if they will be back for the winter break in early January, he added: "Maybe after also. We will not get them before the winter break."
Clement said Danilo's injury could be an issue which requires surgery and confirmed it would likely force him into the January transfer market in search of a striker.
"It was an unlucky situation, it happens in football. Because of the contact, he had an issue with his knee afterwards," he added.
Rangers host Dundee at Ibrox tomorrow before travelling to face Real Betis in the Europa League on Thursday. They'll face Aberdeen in the Viaplay Cup Final next Sunday.
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