Rafa Benitez says he found the booing of Salomon Rondon and the decision to bring him off the bench against Brighton 'difficult to understand'.
Sections of the Goodison Park crowd jeered when Rondon was being readied to come on during the second-half when Everton were 3-1 down.
Rondon then coming on to replace Jonjoe Kenny prompted more boos and Benitez, who has seen other substitutions met with an angry reaction, was at a loss as to why some fans booed.
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"It is difficult to understand," he said.
"You take off a defender and put on a defender when you are losing. normally people are happy with that and, hopefully, can understand that we are trying to do the best for the team."
Everton went on to lose 3-2 with Anthony Gordon netting both for the home side.
