The 30-year-old has featured in 15 games in just 10 weeks for both England and Spurs, often being deployed up front without a striking partner.
However, Villas-Boas believes the forward is keen to continued playing regularly, after growing frustrated at a lack of first-team opportunities last season.
|4/1||Jermain Defoe is 4/1 to score last with Paddy Power when Tottenham take on Southampton|
"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."