Bayer Leverkusen head coach Xabi Alonso reacted to the 0-3 defeat to Atalanta in the Europa League final two weeks after the game.
"At the moment it hurts. It is very painful. Such games should not be forgotten. But I feel that this will be more useful for my development as a coach than winning a treble," CNN Sports quoted Alonso as saying.
Last season, Bayer won the Bundesliga and the German Cup.