Klaassen was in the Ajax side beaten 2-0 in Stockholm by Rooney’s Manchester United in May.
And ahead of tonight’s game against Atlanta, Everton’s £23.6m signing admits he still bears the mental scars.
The Dutchman has made a slow start to his career in English football but is relishing the chance to shine on the European stage against opponents who finished fourth in Serie A last season.
“I still feel the pain from the final,” said Klaassen, yet to score for his new club, despite an impressive goalscoring record in Holland.
“But I didn’t need to lose in a final to be hungry for this.