The 30-year-old has flourished since the Portuguese's arrival as he has gone from a bit-part player under predecessor Harry Redknapp to the side's first-choice striker.
Defoe is also featuring regularly for England, but international football combined with Spurs' domestic and European exertions has raised questions as to whether he can cope with such demands.
The former West Ham man 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."
The pressure on Defoe's shoulders has been intensified by the lack of out-and-out attacking options at Tottenham, although the return to fitness of Emmanuel Adebayor will help lift the burden on the diminutive striker.
Villas-Boas hopes the Togo international will be available after back pain for Sunday's trip to Southampton, where several other key players are set to come back into the reckoning.
"Gareth Bale will definitely return and Adebayor we will have to wait and see," he said.
"Mousa Dembele we will have to wait and see, although he is making good progress.
"We've recovered recently [Kyle] Naughton and Jake [Livermore] so it is opening up a bit for us in terms of people recovering.
"It gives us the ability to have some fresh legs against Southampton."
Spurs will, though, definitely be without Scott Parker, Younes Kaboul and Benoit Assou-Ekotto.
Michael Dawson is also a doubt through illness, which will means much of the team that featured in Slovenia on Thursday evening will be utilised once again at St Mary's.
Spurs were held to a disappointing 1-1 Europa League draw at NK Maribor and now face the challenge of a quick turnaround to face Saints.
"I think we had one of our strongest performances against Aston Villa after a trip to Panathinaikos," Villas-Boas said.
"This is a shorter trip, certainly we don't have the squad in-depth to give us the options other people might have.
"I think what we are trying to do is not just go through in a competition that means a lot to the club, but also educate the players on this intensity of matches that in the end is equal to any team playing in the Champions League.
"It is one day more, obviously, than the others and it is our preference to play on Sunday.
"By that previous example of Aston Villa, it leaves us in a comfortable position and hopefully it won't take its toll."