Brewster had shown signs of getting going in a Blades shirt with two goals in his last three games, before going down with a hamstring issue during the victory over Bristol City.
Heckingbottom revealed that the Blades had sought a second opinion on the injury after receiving an initial “scary” prognosis. And although the results do not seem as damaging as the first, Heckingbottom said: “Rhian has significant damage to his hamstring tendon, but we’re pleased with his prognosis.
“He’ll be out for a while, but he’s responding well to treatment and he’ll be back when he’s back.”
Heckingbottom also revealed that Robin Olsen, the on-loan goalkeeper from Roma, is still not fit after damaging his side on international duty with Sweden.
“Robin is progressing slowly,” Heckingbottom said, “but he’s still not fit.”