The Brazilian right-back is already banned for one game after his dismissal for two yellow cards and will miss the weekend match at home to Birmingham.
Not going quietly: Rafael (left) protests after his dismissal against Tottenham
However by pleading guilty to the improper conduct charge Rafael hopes that the FA will not increase his punishment when they hear his case on Friday.
The FA imposed the charge after seeing TV footage of Rafael haranguing referee Mike Dean in the wake of his dismissal.
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