Portugal coach Carlos Queiroz has told his team not to get carried away by their unbeaten run as they enter the last 16 of the World Cup.
The Portuguese take on European champions Spain on Tuesday in Cape Town after finishing second in their group behind Brazil and Friday's goalless draw against the South Americans marked the 19th consecutive game Portugal have gone undefeated under Queiroz.
But Queiroz said: "Statistics don't mean very much. They might build up our confidence, but we cannot go to the round of 16 just with reputation and statistics. Our players have to prove their worth on the pitch."
Portugal have also kept a clean sheet in 22 of their last 26 matches.
"This shows that we are playing good defence," said Queiroz. "But we have to keep our feet on the ground because now the knock-out round begins and any mistakes can send you home."
Portugal are no strangers to their Iberian rivals, a side they eliminated in the knock-out round of Euro 2004 with a 1-0 victory.
The Spaniards won the European title, however, two years ago in Austria and travelled to South Africa as one of the favourites to win the World Cup.
"I have not analysed any other groups up to now," admitted Queiroz. "I have just focused on my group, which was enough work.
"But now we will prepare to be at our best in our next match.
"The important thing is that we play how we know."