Everton boss Ronald Koeman has revealed that Kevin Mirallas was dropped for Sunday's Premier League clash against Chelsea due to a problem with "his attitude".

The 29-year-old was surprisingly left out of the Everton squad that visited Stamford Bridge at the weekend.

Olympiacos have been credited with an interest in the Belgian international ahead of the close of the transfer window, and Koeman has hinted that the attacker could be allowed to depart before the end of the month.

"He was out because he is struggling to deal with moments in the season and was disappointed," Koeman told reporters.

"Everybody can be disappointed. But I expect from everybody to be part of the team. If somebody is showing that he is disappointed and his attitude is not the same then I have to make decision."

Mirallas has scored 38 times in 177 appearances for Everton since joining the club from Olympiacos in 2012.