The Elland Road faithful began celebrating when Georginio Rutter stabbed home, capitalising on a spill from Bristol City goalkeeper Max O’Leary.
However, the goal was ruled out when Rutter was judged to have been in an offside position.
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O’Leary’s spill was forced by an effort from Sam Byram. When Byram struck the ball, Rutter was stood in an offside position and made a clear attempt to play the ball.
Rutter then had an advantage when O’Leary spilled the ball into his path, another reason to disallow the goal.
Foy told Sky Sports: “Making a decision in a crowded penalty area is always challenging for the officials. When the ball is volleyed towards goal by Sam Byram the eventual goal scorer, Georginio is stood just beyond the second-last opponent – so in an offside position.
“Although he doesn’t touch Byram’s initial shot, he makes a clear attempt to play the ball, and clearly impacts the ability of Bristol City’s goalkeeper to play the ball, who delays his save and spills Byram’s effort, before Georginio taps the loose ball into the net.
“There are two offside offences here, the first is Georginio’s initial action that clearly impacts the Bristol City goalkeeper’s attempt to make the save, and the second is that following a save he gains an advantage for the resultant tap-in by initially being in an offside position. This is a good call by the officials.”
The decision did not prove detrimental to Leeds, who emerged as 2-1 winners courtesy of goals from Daniel James and Joel Piroe.