The Brazil-born Spaniard was rated as a "big doubt" for the match by Jose Mourinho but has come through a light training session without aggravating his minor muscular injury.
Earlier on Friday Jose Mourinho admitted the Brazil-born Spaniard was a "big doubt" for the match, having sustained a minor muscular injury in training on Wednesday.
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But Costa came through a subsequent light training session without aggravating the problem and has therefore been included in the Chelsea squad for the trip to Goodison Park.
"We are trying everything for him to play [on Saturday]," Mourinho told reporters earlier on Friday. "He didn't train for the last two days. Today is the last day.
"We have to try and see if the reaction is positive. If the reaction is positive, we take him and select him on the bench."
Costa has made an impressive start to his Chelsea career, scoring two important goals in his first two Premier League matches against Burnley and Leicester City.