Willock's equaliser left the fans fuming on social media as they slammed the FA for not using the technology throughout the tournament.
An X handle named Clark Kent wrote: "The FA Cup is a mess of a competition. VAR in some rounds but not others. Goalline technology in some games but not others. Goalline technology is a game that has no VAR?"
Gooner_CC wrote: "I understand that there's no VAR, but are you telling me goal line technology is not a standard in English football?? Not saying the whole ball didn't cross the line, but some confirmation would be nice."
Vince wrote: "Is goalline technology that difficult or complicated to use at this stage of the FA Cup. I find it weird that there is no goalline technology. I understand no VAR, but goalline technology, I don't understand."
A fan named JP the match officials as the post read: "Referees in this country are f*cking terrible. That's borderline corrupt. Not even close to being over the line. Utterly f*cking disgraceful."
Famous United fan Mark Goldbridge wrote: "That is so dodgy on Birmingham that. Linesman no way can see that is over the line. Pure guesswork."
Adam Savva wrote: "The whole ball is NOT over the line. That is disgusting officiating."
Arun wrote: "FA Cup is being played in the 20th century lmao....they don't even have goalline technology."