The Dutch must beat the Seleccao by two goals in Kharkiv on Sunday and hope for a Germany victory over Denmark in the group's other clash if they are to progress
The Dutch lost their first two Group B matches but can still qualify for the quarter-finals if they beat Portugal in Kharkiv by more than two goals and Germany defeat Denmark in Lviv.
"We have to go for it here and need Germany to win," the former Borussia Dortmund boss stated at a press conference.
"We know from the start we have to win with a two-goal difference and I have that in mind. We have to go for it and that’s what the tactics will be based on. You’ll see that as well.
"After the Germany defeat we were deeply disappointed but we knew we had to beat Portugal by at least two goals. It gives you a new situation, and I want to go ahead with that.
"This is based on the fact that Germany will win [against Denmark] - I've got nothing to add to that statement.
"The consequences of other games can't really help us right now. We’re just going to play our game and wait and see what Germany does."
Van Marwijk has faced criticism for alienating players during the tournament including Rafael van der Vaart and Klaas-Jan Huntelaar, who have expressed their frustration at being forced to settle for substitute roles.
The 60-year-old, who was in a spiky mood in his pre-match press conference, insists he is happy with the way he communicates with the players.
"I do talk to some of the players and I don't with others,” he added. "I just talk to the players who will be in the team about what we want to change.
"A competition like this with one game left is very different to a league season. We know we have to win 2-0 so the tactics that we choose will be based on that."
A feature of recent clashes between the Netherlands and Denmark has been ill-discipline, with their second round clash in the 2006 World Cup seeing four red cards.
Van Marwijk expects another fiery encounter on Sunday night but has urged the players to keep their cool.
He said: "It’s going to be a very hectic game. We’ve seen lots of yellow and red cards in matches against Portugal in the past. We need to be disciplined. I’ve told that to the players, but they know that already."