Los Ticos have won the neutrals' affection by recording shock victories over Uruguay and Italy to win Group D, before dispatching Greece on penalties to seal a quarter-final berth.
However, Jorge Luis Pinto's side face perhaps their sternest test to date in tomorrow's clash with the Oranje in Salvador, but Ruiz is optimistic that his teammates can continue to defy the odds.
"Saturday's game is like a final for us, but we don't want to stop there," he told FIFA.com.
"Holland is a great team, but I have to be honest and say that we have a good chance of beating them. But we have to take care of a lot of details if we want to win."
Tomorrow's encounter kicks off at 9pm.