The Magpies brought the Frenchman in from Toulouse for 3 million euros during the January transfer window, and Villas-Boas is certain that represents good value.
“Most of their signings have gone straight in and have had the right impact,” he told reporters. “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.”
Spurs made just one signing during the mid-season window, bringing in midfielder Lewis Holtby from Schalke, and Villas-Boas has been pleased with his latest arrival's impact.
“He's made an immediate impact in the team in both games,” he said. “Lewis offers further options playing from the channels coming in.
“We haven't seen him in this position yet, but he finds comfort in that position because played it before for Mainz.
“At the moment he's playing fantastically well. Hopefully we will continue to see him progress.”
The Portuguese coach also called for his squad to keep up the momentum gained from their win over West Brom last time out.
“We want to build a gap over the teams that are chasing us and bridge the gap to those at the top,” he added.
“It can go either way. Everton have a difficult away fixture [at Manchester United] this weekend, Arsenal have one too [at Sunderland].
“If we want to be able to profit in some way from these two fixtures, we have to get the result against Newcastle. We have to do our job.”
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