For Championship clubs, football can often be a game of very narrow margins.
That makes refereeing mistakes all the more significant, especially for teams on a poor run.
Leeds United were winless in four league games going into their meeting with Sheffield Wednesday, and after going 2-0 down they thought they'd restored some hope when Liam Cooper turned home a free-kick.
But the referee ruled it out...because Wednesday were in the middle of making a substitution.
Fans of the away side were incensed.
https://twitter.com/jacktimms92/status/688367124939730944
Really incensed.
https://twitter.com/TomFoy_/status/688367776369631233
Many were unsurprised
https://twitter.com/awinehouse1/status/688363263252385792
There was some of the usual wisecracking.
https://twitter.com/EamoV1/status/688364870673285120
https://twitter.com/MrPaulRobinson/status/688366906798116864
But others took it in their stride
https://twitter.com/lufc_dan/status/688363838127927297
