Much was expected of the Argentine attacker, who cost Spurs £30m from Roma in the summer, but he has so far yet to find the net in any of his eight appearances in all competitions.
Discussing the 21-year-old's situation, Villas-Boas has admitted that he had expected a bit more from him.
"We have been speaking a lot with him. I think getting acquainted to the Premier League is important but he doesn't know the language. (Roberto) Soldado had some knowledge of the language before [he signed] so it was a little bit easier for him," The Independent quotes Villas-Boas as saying.
"With Erik it was a little bit more difficult but we have given him massive, massive help and his family arrived this week. He knows he isn't producing half of what he can produce but he understands the situation now is that he has to compete for his place."
Lamela scored 15 goals for Roma in Serie A last season.