Everton have launched an investigation after an object was allegedly thrown onto the pitch during their 2-0 win over Chelsea on Sunday.
Midfielder Ross Barkley, a Toffees academy graduate, was making his first appearance at Goodison Park since his acrimonious departure in January 2018 and the incident reportedly occurred at a Chelsea corner in front of the Gwladys Street End early in the first half.
No-one was hit by the object and Everton are looking into the matter.
"We are investigating the alleged incident and reviewing footage. If anyone is found responsible for this or other such incidents, the club will take robust action," said a statement from the club.
The alleged incident came two days after the FA, Premier League and EFL issued a joint statement, urging "all supporters to carefully consider their behaviour" at the weekend's games and "all games in the future".
That statement followed high-profile incidences of crowd trouble the previous weekend when Aston Villa captain Jack Grealish was punched by a spectator who ran on to the pitch during their match at Birmingham and Manchester United defender Chris Smalling was shoved by a pitch invader during his side's match with Arsenal.
