Defoe has featured in 15 matches for club and country in the past two-and-a-half months, but Villas-Boas insists he has no concerns about the striker.
"Let's compare it to last year. People were begging for chances and here they are," the former Chelsea manager said.
"Obviously it is a different type of situation, but at this time of the season I am not worried yet.
"You take out the first three games of the season as they were separated by a week, there were international breaks when he played some of the games but not all.
"He still has power and energy in his legs. Also the possibility of him equalling Teddy Sheringham or overtaking him on the top 10 of Tottenham's goalscorers is something that motivates him."