Spurs have established themselves as one of the chief title contenders in the past two seasons under Mauricio Pochettino and are well-placed to earn Champions League football for a second consecutive campaign this term.
"We want to start well and especially focus on the game and not what's going on around (us). We will, as usual, try to play our own football and I am confident that we can show something in these fantastic circumstances [at Wembley]," Vanhaezebrouck told reporters.
"It will be a fantastic moment for our club and our team. I didn't think Tottenham underestimated us in the first game and they won't underestimate us either [tonight]. They have said that they will go for it 100% – we did that already in the first leg and we will do so again.
"Dembele is one of the key players for Tottenham. Without him, they would not stand in the place where they are now. He plays a very important role in the team."
Thursday's match will be Gent's 100th competitive European outing.