André Villas-Boas watched his Tottenham Hotspur side move seven points clear of Arsenal and then spoke of his confidence they would not allow Arsène Wenger's team to come out of their "negative spiral" to retrieve the position.

A 2-1 win courtesy of Gareth Bale's 10th goal in eight matches, quickly followed by an Aaron Lennon effort – more examples of Arsenal's vulnerability in defence – have left Spurs in a position of strength as they try to finish above their old rivals for the first time since 1995.

Arsenal were 10 points behind Spurs at one stage last season before overhauling them in the final few weeks, but Villas-Boas believes his team have struck a significant psychological blow. "The difference this year is that we are on an upward spiral in terms of confidence whereas they are in a negative spiral and once you get into that negative spiral it's difficult to get out of it," he said.

"Last year Arsenal made up the difference and we all know what happened at the end of the season, but the difference this time is we are extremely confident whereas they are in a low at the moment. For them to jump back from here is going to be very difficult, although they can do it. Nothing is finished yet.

"We have to keep our feet on the ground because we have some difficult games coming up and everything is still possible. We just have to get as many points as possible but the players have been absolutely outstanding. They have made it public that they want to be in the Champions League and their effort has been tremendous."

The defeat leaves Arsenal in danger of not qualifying for the Champions League for the first time since 1997-98 and Wenger admitted that Spurs are now the overwhelming favourites, with 10 games of the season to go. "It's a massive challenge [to catch them], massive. I said before the game that we couldn't drop points and I maintain that."

Wenger was particularly dismayed by his team's defending as they went 2-0 down with two goals in as many minutes. "It's very frustrating because we had the best defensive record away from home in the league before today. But it [poor defending] has happened to us many times this season and only in big games. It's difficult to explain. There's no common theme, it's different problems. But you make it difficult for yourselves."

Spurs, in contrast, defended manfully after Per Mertesacker had made it 2-1 with a 51st-minute header that deflected in off Bale. "There is still a long way to go but it's a good day," their captain, Michael Dawson, said. "We want to be back in the Champions League. I think it showed in our celebrations after the final whistle."

Emmanuel Adebayor was taken off on a stretcher after landing awkwardly in an aerial challenge and Mousa Dembélé was also forced out of the match but Villas-Boas said both players should be fit for Thursday's Europa League tie at home to Internazionale.

Spurs can extend their lead next weekend when they travel to Anfield to play Liverpool while Arsenal do not have a fixture.