Euro 2016 winners Portugal take on 2010 World Cup fourth-placed side Uruguay in the last 16 of the tournament on Saturday.
A late Iran penalty saw Portugal qualify for the knockout stages, having snatched a late draw with Spain thanks to a Cristiano Ronaldo hat-trick and beating Morocco by a slim margin.
Coach Fernando Santos will have no issue upsetting the odds after Portugal's slow start, having coached them to European Championships glory two years ago despite winning only one game in 90 minutes.
Ahead of Saturday's game, he knows Ronaldo and his fellow forward players will have to be in top form to upset a Uruguay side who are yet to concede a goal in this World Cup, and one who found their scoring boots in a 3-0 win over Russia to top their group last week.
"They are a typical South American side," said Santos.
"It's not just in this World Cup that they have not been conceding goals. It has been like that for the whole of 2018. Oscar Tabarez is the longest-serving international manager. That means he has a very strong relationship with his players."
One of Uruguay's biggest concerns will be that of Ronaldo, who has four goals in the tournament so far, and could have had another had he not missed a second-half penalty against Iran.
Tabarez, who is in his 14th year as Uruguay manager, albeit across two spells, is understandably planning that his side will have to work as a team to contain the five-time Ballon d'Or winner.
"Cristiano Ronaldo is one of the best strikers in the world," Tabarez said. "He has a great potential obviously and in planning the match, especially focusing on the opponent and considering the level that every player has … what Ronaldo has on top of the qualities is that he's the leader of that team.
"That is an additional factor. There is not a single player that can contain him there. Not just [Diego] Godin. We will have to work collectively in order to try and contain him or in order to try and limit the effect he can have."
Clubless William Carvalho could miss the game for Portugal, having been absent from training in the build-up with a minor injury, but Gelson Martins and Raphael Guerreiro are fit to start.
Uruguay defender Jose Gimenez, who scored their first goal of the tournament, should also be ready to return after sitting out their final group game with Russia.