The Aussie defender sustained a knee injury playing for the under-21s against Norwich City.
The former Melbourne Heat defender, who has returned on loan from Bradford City, was captain of the United second string against the Canaries.
Toon coach Willie Donachie said: "Curtis went for an X-ray and hopefully it is not too bad.
"He is a great kid. He is so honest and that is why he went in for the tackle.
"Hopefully, it is not too bad but we will not know the situation until later today.
"He took a kick to his knee, but both knees clashed together."