Louis van Gaal's men won Group B with three wins out of three, with the highlight arguably the 5-1 drubbing of world champions Spain in their opening game.
However, speaking ahead of the last-16 tie with Mexico on Sunday, Robben confesses that he was less optimistic about the chances of the Oranje at this tournament.
He told De Telegraaf: "Ahead of the tournament, we did not expect this. Although, I did not have as bad a feeling about the World Cup as most people back home.
"It's simple: win three times and we're in the final of the World Cup. We must realise that."
Robben has scored three of his country's 10 goals so far in this tournament.