Ghana coach Otto Addo urged his players to seek inspiration from Saudi Arabia and Japan's victories over World Cup heavyweights Argentina and Germany when they take on Portugal in their opening Group H match on Thursday evening.
"We have quality and can compete," said the former Ghana international. "We have to be brave and self confident.
"We have seen in some of the upsets that little things decide the games and we expect it to be the same against Portugal."
The Europeans go into the tie at the Stadium 974 as overwhelming favourites.
Fernando Santos's squad oozes class with experienced internationals such as Cristiano Ronaldo, Bernardo Silva, Pepe and Bruno Fernandes. That wiliness is bolstered by rising talents such as Diogo Dalot and Joao Felix.
Of the 26-man squad only skipper André Ayew and his brother, Jordan, have played at a World Cup.
"Portugal will go into the game as favourites," conceded Ghana skipper André Ayew;
"But that's on paper. But it's on the field that it matters," added the 32-year-old.
"We believe in ourselves and we are going to do eveything possible to make it difficult for them."
The prelude to the game has been overshadowed by Ronaldo's departure from Manchester United following a TV interview in which he hit out at the club hierarchy.
The 37-year-old is yet to reveal his next destination.
"I don't know if the news around him will disrupt Portugal's preparations," said Addo.