Chelsea players fear a refs' backlash over their stand against Mark Clattenburg.
The Daily Mail says players fear the case could result in unwelcome tension between themselves and officials as they battle for the Barclays Premier League title.
John Mikel Obi's agent John Shittu flew into London on Monday as the FA's governance team began taking recorded statements from players.
Chelsea's external legal team were also present after Mikel was asked whether he wanted them to pursue a case against Clattenburg with the FA, as the club prepare for another lengthy spell in the spotlight.