The former Liverpool man damaged the muscle away at Peterborough late last month, just as he was appearing to really get going in a United shirt following his club record move.
Here’s how a selection of Blades fans reacted on Twitter to the news, as Brewster prepares to go under the knife tomorrow …
@DavidMckenzie89: Absolutely gutted for the lad, just when he was getting a solid run and finding the back of the net. Hopefully he'll have a chance at a full preseason and can fire on next season
@bulmer1889: Hopefully it sorts the problem out and he’ll be good to go next season. Tough on him and us he was beginning to look like the player we thought we had bought. Hope it goes well for him
@Ryanelvin2411: He was flying too. Wishing him a speedy recovery
@Michael89300079: Very tough on the boy wishing him a speedy recovery & a successful rehab. UTB
@daneshaw8: He’s unlucky with that. He’ll come back stronger next season
@elliejaneF1: Gutted. He was just coming into his own, hopefully a speedy recovery
@_LH9_: Gutting news for Brewster. Really looked to be kicking on under Hecky. Right decision to recall Jebbison and hopefully he can continue his form from his time at Burton
@RichardGraves1: Massive blow for the Blades and for a player who was just finding best form in front of goal!