Playing for Castilla in their 2-2 draw with Atletico B, the €45m signing was bitten by opposition captain Tachi.
Lopetegui said: "(I saw it) they gave eachother a hug and I stay with the positive.
"He has a fantastic talent. He is going to be a great player.
"He is adapting in the way we see best. He is training with the first team and we are deciding. I will not advance what we are going to do."