Spurs reached the last 16 of the Europa League on Thursday, edging out Ukrainian side Dnipro over two legs.
The reward is a tie against Benfica and the Belgian admits: "It is a very important game.
"Some people say that for English teams, the Europa League is not so important. But for us I think it's very important.
"We want to achieve something this year and making progress in Europe is a big help."
As for facing Cardiff at White Hart Lane on Sunday, the midfielder added: "It is the right time for us to get them at home after our recent results at White Hart Lane and I think everybody is very happy and maybe a bit more confident after the Dnipro win.
"We hope now that we can see off Cardiff correctly and professionally. It was an important thing for us to beat Dnipro."