Fabregas (right) was injured for the match but entered the pitch at full time
Arsenal midfielder Cesc Fabregas and Hull manager Phil Brown have been charged with improper conduct by the Football Association.
The charges relate to Arsenal's 2-1 FA Cup fifth round replay win over Hull.
Fabregas did not play because of injury but came on to the pitch at the final whistle and is later alleged to have spat at Hull assistant Brian Horton.
Brown will also have to answer to the FA for his comments about referee Mike Riley after the game on 17 March.
"Fabregas faces two charges of improper conduct relating to his conduct on the pitch following the game," read an FA statement.
"One charge concerns his behaviour in coming on to the pitch after the final whistle, the second charge relates to an alleged spitting incident. The charges are based on submissions from Hull City and video evidence.
I am very positive that there was enough evidence in what I have seen that the case should have been dropped
Arsenal manager Arsene Wenger
"Brown is charged with improper conduct and/or bringing the game into disrepute in relation to media comments made after the game concerning referee Mike Riley.
"Fabregas and Brown have until 12 May to respond."
Spain international Fabregas faces a ban if the charges are proven and, although that would include domestic matches, he would be eligible for Champions League games.
"I dont know if we will appeal - I will see what we can do about that," said his club manager Arsene Wenger.
"At the start, I am not a great fan of appealing because I said we are very open to co-operate and now I don't think we should stop that.
"I am very positive that there was enough evidence in what I have seen that the case should have been dropped."
But Hull chairman Paul Duffen told the club's website: "I have always welcomed the Football Association's investigation into events at the Emirates Stadium following the final whistle of our FA Cup final whistle.
"It's no surprise to me that the FA has decided to bring the charges they have announced as I have always been confident in Phil Brown's and Brian Horton's accounts of events on that day.
"I will not comment further at this time as this matter is the subject of a disciplinary charge but I have always known that Phil and Brian tell the truth."
Fabregas, who missed more than three months because of a knee injury, has denied he spat at Horton.
He said: "I have never done this [spit] in my whole career, so why would I when I am not even playing?"
Hull City submitted their own evidence to the FA at the end of March.
The club handed in statements from Horton, Brown and fitness conditioner Sean Rush to the FA.
"There is an independent solicitor representing us and hopefully there will be no bias towards any one club," Brown told the Hull Daily Mail.
"We really just want the truth to come out. If the truth comes out then we've got nothing to worry about."
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