The FA is investigating video footage of Troy Deeney's reaction after the Watford striker scored a penalty against Chelsea during the Hornets 4-1 win on Monday.
The 29 year old appeared to make an obscene gesture to the crowd after he put Watford ahead at Vicarage Road.
The FA is awaiting referee Mike Dean's report to ascertain whether he saw the incident before any decision is made. If the action was not seen by the match officials then he is subject to a standard retrospective two-game ban if a charge of making an obscene gesture is proved.