Lillyman played only 10 minutes of the Warriors 26-10 trial win against Gold Coast Titans before leaving the field with an arm injury.
Warriors head coach Brian McClennan fears the Queensland origin forward will be out for some time.
He said: “Unfortunately it doesn’t look good for Bull (Lillyman).
“He’s going to be missing some games.”
McClennan said more details about the extent of the injury would be confirmed in the next day or two.