Coach Luiz Felipe Scolari was elated to secure Portugal's place in the second round of the World Cup for the first time in 40 years.
Goals from Deco and a Cristiano Ronaldo penalty resulted in a 2-0 win over Iran and Scolari said: "This is a historic moment for Portugal.
"It's the first time in 40 years they have come so far. We're elated.
"We still want to beat Mexico to ensure first place in the group," the Brazilian coach added.
It was Portugal's second win in Group D following their 1-0 triumph over Angola in their opening fixture.
And Scolari added: "We played better than against Angola. We showed some of our skill."
Portugal last qualified for the second phase of a World Cup tournament in 1966, when Eusebio guided them to a third-place finish.