Fernando Santos's side only need a point to be certain of finishing at the top of the section, while South Korea need to overcome the European nation to stand any chance of progressing to the round of 16.
Match preview
South Korea opened their Group H campaign with a goalless draw against Uruguay on November 24 before suffering a 3-2 loss to Ghana in their second match at the competition on Monday.
Paulo Bento's side managed to fight back from two goals behind to level the scores at 2-2 just past the hour at Education City Stadium, but Mohammed Kudus's second of the match in the 68th minute secured all three points for Ghana, putting them in pole position to join Portugal in the round of 16.
South Korea are third in the section on one point, but they can still qualify for the knockout round of the competition. Indeed, Bento's team will need to overcome Portugal to stand any chance of progressing; if they do beat Santos's side and Uruguay overcome Ghana, then goal difference would separate the two sides.
The Tigers of Asia last managed to reach the knockout round in 2010, with their last two World Cups ending in the group stage.
It was always going to be a tough ask for them to make it out of this section considering the strength of their opposition, but they are in the argument at this stage, and the fact that Portugal have already qualified could work in their favour on Friday.
Portugal, as mentioned, have already secured their spot in the knockout round of the competition, but they would guarantee first spot in the group with a win or a draw in this match.
Santos's side started their World Cup with a 3-2 victory over Ghana, and the match saw saw Cristiano Ronaldo become the first men's player to score in five World Cups.
Portugal were then 2-0 winners over Uruguay on Monday, with Bruno Fernandes scoring twice for the European nation to secure their spot in the last-16 stage of the tournament. Ahead of the final matchday, the team are top of the section, three points clear of second-placed Ghana, who are in pole position to secure the second qualification position.
A Selecao finished third at the 1966 World Cup and fourth at the 2006 competition, but they have not been past the round of 16 since the 2006 tournament, with two of their last three World Cups ending in the first knockout round, while they actually failed to make it out of the group in 2014.
Ahead of the tournament, Portugal were not considered to be one of the favourites, but they have impressed in their opening two matches and will certainly be looking to finish their group-stage campaign with a strong result against South Korea.
South Korea World Cup form:
D
L
South Korea form (all competitions):
W
D
W
W
D
L
Portugal World Cup form:
W
W
Portugal form (all competitions):
L
W
L
W
W
W
Team News
South Korea have not been able to use Hwang Hee-chan in the tournament thus far due to a hamstring problem, and the forward remains a major doubt for Friday's contest.
Son Heung-min will again be a certain starter for Bento's team in this match, with the 30-year-old set to win his 107th cap for the national side, while Napoli's Kim Min-jae will line up in the middle of the defence.
Cho Gue-sung scored twice against Ghana last time out and will again lead the line for South Korea, while Kwon Chang-hoon should retain his spot in a wide position.
There should also be a spot in the middle of the park for Hwang In-beom.
As for Portugal, Nuno Mendes had to be substituted in the latter stages of the first half against Uruguay last time out, and the defender will be unavailable for selection here.
Danilo is also out with fractured ribs, while Otavio is a doubt with the injury that forced him to sit out the game against Uruguay last time out.
Raphael Guerreiro should come back in for Mendes at left-back, but it should otherwise be the same side that took to the field for the first whistle in the team's second game.
Fernandes should again support the front two of Ronaldo and Joao Felix, leaving Rafael Leao on the bench despite the AC Milan attacker impressing in his two appearances off the bench at the competition.
South Korea possible starting lineup:
Seung-gyu; Moon-hwan, Min-jae, Young-gwon, Jin-su; Woo-young, In-beom; Chang-hoon, Woo-yeong, Heung-min; Gue-sung
Portugal possible starting lineup:
Costa; Cancelo, Pepe, Dias, Guerreiro; Bernardo, Neves, Carvalho; Fernandes; Ronaldo, Felix
We say: South Korea 1-2 Portugal
This is likely to be a tough match for Portugal, as South Korea will need to go all out in search of the three points. There is no question that Bento's side are capable of securing a victory, but Portugal have the superior quality in their squad, and we are expecting the European nation to move onto nine points in the section.