But Ben Arfa won it from the spot after he was fouled by Aaron Lennon, picking himself up to slot past Brad Friedel.
A trip to the north east always looked a tricky start for Villas-Boas, against a Newcastle side aiming to build on their fifth-place finish last time out.
The Magpies were last season's surprise package but this time it is Spurs who are the unknown quantity, beginning life under a new manager who is rebuilding his reputation after his ill-fated stint at Chelsea and still constructing his squad.
That process will continue if and when Luka Modric leaves for Real Madrid before the end of the month and, on this evidence, Villas-Boas will surely intensify his efforts to sign Manchester City striker Emmanuel Adebayor to bolster his attacking options.
Spurs had the better of the first half, new signing Gylfi Sigurdsson denied by Tim Krul - although the £8m Iceland midfielder did not know he had already been wrongly ruled offside.
Guy MowbrayBBC Match of the Day commentator
"It's a winning start for Newcastle United. No points on the board for Spurs boss Andre Villas-Boas, who might feel a little unlucky. They were the best team in the first half but Newcastle took their chances in the second half."
More opportunities followed before the break, with Defoe cutting into the area to prod a shot against the post, before Bale met Lennon's enticing cross with a header that looped back off the bar.
But Spurs could not make their chances count while, in contrast, Newcastle put away their first opening of note nine minutes after the break.
Kyle Walker failed to deal with Danny Simpson's cross and his header fell at the feet of Ba, who turned to curl home an unstoppable shot and end his run of 14 games without a goal.
The Magpies had Pardew sent off soon afterwards, the Newcastle boss pushing linesman Peter Kirkup after claiming the ball had gone out of play in the build-up to a Sigurdsson shot that flew wide.
And Pardew soon had more to get angry about from his vantage point high in the stands.
Villas-Boas rues wasteful Tottenham finishing
Defoe saw his header from a Lennon cross hit Davide Santon before being scrambled on to the post by Krul, but, with the Newcastle defence static, he reacted quickest to fire home the loose ball.
Spurs were level for less than five minutes, however, as Ben Arfa delivered a timely reminder of what he is capable of when given space in the final third.
He burst into the area and, after being brought down by a combination of mis-timed challenges by Rafael van der Vaart and Lennon, sent Friedel the wrong way from the spot.
There was no way back from there for Tottenham, who only had teenager Harry Kane in the way of strikers to bring on from the bench and did not come close to salvaging a point in the final 10 minutes.
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