
The defender missed Tuesday night's defeat to Norwich after coming off against Oxford United last weekend.
Sondre Langas came into replace him with the Norway international making his first start since a 1-1 draw with West Brom in January.
Eustace says the former Birmingham defender has not been in full training but did not rule him out of the QPR game.
"We'll have to wait and see on Dion," said Eustace.
"Obviously he hasn't trained since the Oxford game.
"He hasn't been up with the group or on the grass, so, let's just wait and see on Dion.
"I think his performances this season have been excellent and he's really impacted the group, which was what we wanted.
"We'll just see if he's available, if not, then we'll wait for next week possibly."
Rhian Brewster, Patrick Agyemang, Bobby Clark and Callum Elder are already on the sidelines. They will all be unavailable for the game tomorrow.
Derry Murkin is also out of the squad after picking up a hamstring problem against the Canaries.
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