Portugal and S.Korea's supporters cheer before the start of the Qatar 2022 World Cup Group H match at the Education City Stadium in Al Rayyan, Doha, on Friday. AFP / Reuters / AP

Ronaldo, who scored against Ghana in Portugal's opening game to become the only player to have netted in five World Cups, had missed training on Wednesday.

Coach Fernando Santos made six changes from the team that beat Uruguay to clinch qualification for the knock-outs, with Bruno Fernandes, Bernardo Silva and Joao Felix among those rested.

Cristiano Ronaldo during the warm up before the match against South Korea in Doha. Reuters

Benfica's Joao Mario and Wolves midfielder Matheus Nunes come in, along with Manchester United full-back Diogo Dalot, who replaces injured Paris Saint-Germain defender Nuno Mendes.

Portugal need just a point against South Korea to clinch top spot, while the Asian side have to win and hope the result in Ghana's clash with Uruguay goes their way too.

Tottenham forward Son Heung-Min captains the Koreans, still in search of his first goal at the tournament.
Napoli centre-back Kim Min-jae is on the bench having suffered with a calf injury at the tournament, while dynamic Mallorca winger Lee Kang-in starts, as one of three changes.

Starting line-ups:

South Korea (4-2-3-1)
Kim Seung-gyu; Kim Jin-su, Kim Young-gwon, Kwon Kyung-won, Kim Moon-hwan; Jung Woo-young, Hwang In-beom; Lee Kang-in, Lee Jae-sung, Son Heung-min (capt); Cho Gue-sung

Coach: Paulo Bento (POR)

Portugal (4-2-3-1)

Diogo Costa; Diogo Dalot, Antonio Silva, Pepe, Joao Cancelo; Ruben Neves, Matheus Nunes; Ricardo Horta, Joao Mario, Vitinha; Cristiano Ronaldo (capt)

Coach: Fernando Santos (POR)

Referee: Facundo Tello (ARG)

Agence France-Presse