Netherlands must beat the Portuguese by two clear goals, coupled with a German win against Denmark, to avoid being eliminated in the group phase of a major championship for the first time since Euro 1980.
"We need Germany to win but we know from the start we have to win by two goals and I will keep that in mind," said Dutch boss Bert van Marwijk.
"We have to go for it, that's what the tactics are based on. The tactics will reflect that situation."
The place of veteran midfielder Van Bommel, who was substituted at half-time of Wednesday's 2-1 defeat by Germany, has been heavily scrutinised by the Dutch media.
Did you know?
Netherlands have lost two group games in the same European Championship finals for the first time in their history
The ex-AC Milan and Barcelona player sat alongside father-in-law Van Marwijk in a pre-match press conference, leading to suggestions he would definitely start the crucial fixture.
But when asked about his team selection, a spiky Van Marwijk told reporters: "As soon as we begin, you start talking about the first XI. You can make your own conclusions."
Portugal head coach Paulo Bento
knows his side could still go out at the group stage,
even if they beat the Dutch,
after taking three points from their opening two games.
But skipper Cristiano Ronaldo and his team-mates could also lose by one goal and go through to the last eight.
"We will fight to the very last minute to achieve our goals," said Bento. "I am always very optimistic.
"If I didn't believe in the possibilities to succeed, I wouldn't be here. We believe in a great result."
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