Portugal midfielder William Carvalho is determined to help his team avoid becoming the victims of another World Cup shock against Switzerland in the last 16 on Tuesday.
After Saudi Arabia beat Argentina and Japan won against both Germany and Spain, among other surprise results, the more fancied sides are wary of slipping up.
Australia came close to taking Argentina to extra-time on Saturday and Carvalho is staying cautious ahead of Portugal's match.
"I'm sure we will be facing a Switzerland team with lots of ball possession, and we're forewarned about that," the Real Betis midfielder told a press conference Sunday.
"There have been really big surprises, that's a fact, so we need to be focused from the very first minute to the last so that things go our way."
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Portugal lost their final group match 2-1 against South Korea, but had already qualified for the knockouts and remained in top spot.
"Nobody likes to lose, we have to analyse the match and learn our lessons so that doesn't happen in the future," said Carvalho.
"I think Portugal need to play like we did in the first two matches, united from start to end.
"We know that we are up against a very tough opponent. The details will make all the difference. We need to be ready."
Carvalho scored as Portugal routed Switzerland 4-0 in June in the Nations League, but a week later they fell to a 1-0 defeat against the same opponent.
"We lost and we won, so we know they will be a tough opponent, but what I can tell you is Switzerland will face a totally focused Portuguese team and we will do our utmost to win the game," he added.