The Blades’ top scorer and talisman only made his return from a hamstring injury off the bench against Cardiff City last time out, and misses out against QPR tonight after damaging a calf in training.
With only two games remaining, Sharp’s absence would be a significant blow to United’s hopes of first sealing their play-off place, and then looking to win the end-of-season shootout and get back into the Premier League at the first attempt.
“It’s his calf,” Heckingbottom said before kick-off in the capital.
“If you’d seen him train on Monday you’d have thought he was an 18-year-old boy excited to make his debut.
“And we were excited to have him back, not just for his goals but that experience and someone who’s been here before.
“But unfortunately we’ve not got him but we have enough good players out there. It might limit our options from the bench but it’s an opportunity for other players and we have more than enough good players out there to get some points.”
Asked how bad the damage is, Heckingbottom revealed: “It'll be weeks, not days.
“We’re going to do all we can, and Billy will do all he can, to be fit if we can get this season extended.”
After tonight’s game at QPR, the Blades bring the curtain down on their regular season next weekend at home to champions-elect Fulham.