Ahead of their Europa League round 16 second-leg clash with AZ Alkmaar, Vicario says the players still believe in Postecoglou's methods.
Spurs must overcome a 1-0 deficit at home to reach the Europa League quarterfinals.
Vicario said: "Yes, I can say that his approach has been very, very committed since day one when he joined here.
"He delivered to us the same way to play the game because he truly believes in this. We can be successful in this way and we are fully behind him, fully trying to do the right things that he believes are working for us.
"We are very, very committed to doing that and we have proved that. When we are at 100 per cent here in the brain and very, very committed to that I think we proved and showed what we can do.
Vicario added: "We know exactly what the game means tomorrow night, we are very conscious of it, and we just want to win the game.
"In terms of pressure, every Sunday and Thursday for six months we are dealing with that. It’s about getting in the best mindset to face AZ. It will be a big clash and we are very ready to play this game.
"The pressure is on us because we play the game, so we have to deal with that. But we are used to dealing with pressure day by day because we play every three days. We know the importance of the game tomorrow, for everyone at this football club, for us players, for the fans especially.
"But I think with all the support we will have tomorrow in the stadium, it will be an exciting night. We are really looking forward to playing tomorrow."