The Magpies snapped up Sissoko up for a nominal fee last month after the France international had been frozen out by his former club Toulouse following his failure to sign a contract extension.
The 23-year-old made an instant impact, impressing against Aston Villa before scoring a vital brace to snatch a win for the north-east side against European champions Chelsea last weekend.
Tottenham, along with a host of other top European clubs such as Juventus and Inter Milan, were thought to be interested in signing Sissoko, but the considerable Gallic contingent in the St James' Park dressing room convinced the dynamic midfielder to move to Tyneside on a six-and-a-half-year contract.
Villas-Boas is a big fan of Sissoko, and Newcastle's other January signings like Mathieu Debuchy and Yoan Gouffran, so he knows his team will have to be on their guard when the Tynesiders arrive at White Hart Lane on Saturday lunchtime.
"Most of their signings have gone straight in and have had the right impact," the Spurs boss said.
"Sissoko was a great grab. A couple of years ago he was being linked with the top clubs in the world and to get him at such a low price was a massive coup for them."
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