Al Rayyan (Qatar), Dec 1 (IANS): With Portugal already through to the knockouts at the ongoing FIFA World Cup in Qatar, their captain and superstar Cristiano Ronaldo may not play against South Korea in the final group match on Friday, Portugal's coach Fernando Santos said on the eve of the match.

"Ronaldo will train and if he's good to go, he will play," Santos said at a pre-match press conference at the Main Media Centre in Al Rayyan, west of Doha, on Thursday. "I think it's 50-50. We'll decide after watching him in our training session."

Ronaldo has been Public Enemy No. 1 among South Korean football fans since sitting out an exhibition match for Juventus in Seoul before some 65,000 fans, reports Yonhap.

Santos said any question about that incident should be directed at Ronaldo and Juventus, and added, "I think Ronaldo has great respect for South Korean people and players."

Portugal beat Ghana 3-2 and then Uruguay 2-0 in Group H to secure their spot in the knockout stage. South Korea, on the other hand, had a goalless draw with Uruguay before losing to Ghana 3-2. South Korea must beat Portugal on Friday at Education City Stadium, also in Al Rayyan, and then hope Uruguay beat Ghana or the two countries end in a draw the same evening.

Santos said Portugal will "do our best" to win the group, but also hinted he may make some lineup changes compared to the two previous matches. "Some of our players are dealing with fatigue, and it could lead to injuries," Santos said. "We have to be careful. I'll think long and hard about what our starting lineup will be."

Santos said South Korea, despite getting just one point out of their first two matches, have played very well and they are not to be taken lightly.

"They are fast on offense and very well organized on defense," Santos noted. "I think they are a well-trained and well-prepared team. And we have to keep evolving, too. I have a tremendous amount of confidence in our players."

If Portugal win Group H, they will likely avoid facing Brazil in the round of 16. Santos said he wasn't yet worried about the knockout matchup at this point and he was only concentrating on getting his players physically ready for upcoming matches despite a quick turnaround.

Teams have been playing group matches with three days of rest in between, and Portugal's first knockout match will be next Tuesday.