Sheffield United are gunning for Premier League promotion this season.
Leeds and Norwich are also vying for the top two spaces in the Championship.
The Blades played Aston Villa in a crunch tie to kick off the weekend tonight.
And Sharp fired his side in front on 10 minutes from a set piece.
Ex-Leeds striker Sharp converted his chance in front of the net – but could only celebrate after the referee had given the goal.
The ball was blocked on the line by Villa player Tammy Abraham and it appeared as first as though play would continue.
But referee Tony Harrington blew his whistle to confirm the goal.
Action replays showed that all the ball had indeed crossed the line.
But Leeds United fans were still not happy.
One fan wrote: “Billy Sharp was never this good for us #lufc”
Another wrote: “One of Cellino’s biggest crimes was getting shut of Billy Sharp. #lufc”
A third put: “I love how we got rid of Billy Sharp. He’s just scored 20 goals this season…#lufc”
And a fourth tweeted: “If only billy sharp had scored so easily for us @LUFC”
Sharp, 33, has now scored 21 goals for Sheffield United this season.
He joined the Blades from Leeds back in 2015.
Sharp played just one season at Elland Road, scoring five goals in a middling campaign for the West Yorkshire side.