Moscow: Portugal coach Fernando Santos and defender Pepe agreed on Tuesday that the side's upcoming Group B World Cup match against Morocco will be challenging.
Portugal, who opened their World Cup campaign with a 3-3 draw against Spain, will face Morocco on Wednesday.
"We have to be very attentive. To show respect and humility against the opponent to be able to build by making use of our capabilities," Santos told reporters at Moscow's Luzhniki stadium.
He described Morocco as a dangerous, experienced team with a strong defense and tactically savvy players.
Santos said he hoped that Portugal captain Cristiano Ronaldo, who had a hat trick against Spain, will show the same form against Morocco.
Pepe echoed his coach's view that Wednesday's match will not be easy.
"Our only objective is this match," the defender said. "This is one of the most important matches."
Spain and Portugal are tied for second in Group B with one point each, while Iran leads the group with three points after beating Morocco 1-0 last Friday.