Mikel Arteta was impressed by Everton signing Segundo Castillo's scoring performance in last week's 2-2 draw with Standard Liege.
He said: "I think Castillo has done really well already and it was a shame (Marouane) Fellaini was unavailable because he is also looking like a great player.
"They are players with aggression and I think they can be here for a long time."