Bert van Marwijk has conceded there is an "uncertainty in the players' heads" ahead of Netherland's crunch Group B meeting with Portugal.

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Despite being tipped as contenders to win Euro 2012, Netherlands are staring at a group stage exit from the competition after failing to pick up any points from their matches against Denmark and Germany.

Their fate will be decided on Sunday when they tackle Portugal. The Dutch need to achieve a victory by two clear goals and hope that Germany defeat Denmark in the other match.

Van Marwijk said. "The players know exactly what we want from them as they showed at the beginning of the match. But if you have a certain kind of uncertainty within your team and in the player's heads, then that is the most difficult thing to deal with.

"We think Germany will beat Denmark and so we have to win against Portugal. History tells us they are not the easiest opponents for us so we need to be patient. But we also have to play in a way in which enables us to score, and I'm convinced that if we score once, we will get a second."