Yaya Toure may miss Manchester City's biggest ever clash with neighbours United.
The Daily Telegraph allege that the Football Association are reviewing photographic evidence which appears to show him making an obscene gesture towards Wolves fans.
The incident occurred in the 42nd minute of City's 2-0 win at Molineux on Sunday, and images of the Ivory Coast international appearing to flick a V-sign at home supporters soon began circulating on Twitter.
Toure, named in the Premier League Team of the Year at Sunday night's PFA awards, has emerged into a vital component of Roberto Mancini's title-challenging machine.
He has been absent for the Citizens' February defeat at Everton and his early withdrawal through injury away to Arsenal on Easter Sunday was a key factor in their loss at the Emirates.
Recently ridiculed regarding inconsistencies in their retrospective punishments, the FA would risk more criticism should they take no action against the 28-year-old.
Liverpool striker Luis Suarez was fined £20,000 and banned for one match in December after a similar incident.
The Uruguayan brandished his middle finger at Fulham supporters after the Reds lost 1-0 at Craven Cottage.
City lie just three points behind United after the Reds drew 4-4 with Everton at Old Trafford on Sunday.
The champions travel to Eastlands next Monday knowing that if they lose they will relinquish top spot on goal difference.