The England international netted from close range to peg back the hosts after Demba Ba's opener, though Spurs went on to lose the match 2-1.
Defoe, who hit a stunning winner for England against Italy last week, struggled to hold down a regular spot under Harry Redknapp last season but still managed to notch 17 goals in all competitions.
Spurs are chasing further striking reinforcements but the Portuguese coach says that the striker accepts this situation and that he will remain a key part of the squad if another forward is signed before the end of the transfer window.
|28/1||Jermain Defoe is 28/1 to be the top Premier League goalscorer in 2012-13 with bet365|
Villas-Boas told reporters: "He always has this killer instinct. He scored in midweek for his country, scored for us during pre-season and again here [at Newcastle].
"He is showing that touch that we need up front. Jermain accepts that we are looking for one more striker because the team is in need of that, but when we have them all together the quality of the player is tremendous.
"It is a different situation for him now. I have nothing to do with anything that happened in the past. He is our striker, is playing extremely well, is full of confidence and has been deadly in front of goal."