Manchester United's Patrice Evra has denied the charge of improper conduct brought against him for his part in a fracas at Stamford Bridge last season.
Chelsea groundsman Sam Bethell has also denied the charge of improper conduct.
The row started when United players, including Evra, were warming down after a 2-1 league defeat to Chelsea and were asked to move by the Blues groundstaff.
Personal hearings have been requested by both Evra and Bethell, although a date has still to be set.
Bethell faces the additional charge of using abusive language aggravated by reference to nationality and or race, which he also denies.
Chelsea reacted strongly to the charge levelled at their groundsman, issuing a statement.
It read: "We believe there is no foundation whatsoever to claims that the incident which occurred after the Manchester United match on April 26 involved comments based on nationality or race, which has led to an FA charge against one of our employees.
"Chelsea FC condemn all forms of discrimination in football and society.
"Such allegations against our club are extremely serious and Chelsea will not be making any further comment until we have assessed all the implications of the charge."
Manchester United and Chelsea both submitted reports into the fracas which took place at Stamford Bridge on 26 April.
The Football Association (FA) took witness statements during their investigations.
"The charges are the result of a thorough investigation conducted by the FA over the last three months," read an FA statement .
"In bringing the charges, the FA used video evidence, CCTV footage and various witness statements from individuals present ."
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