MANAUS - Lingering doubts about the fitness of world player of the year Cristiano Ronaldo have left Portugal in disarray ahead of their World Cup Group G clash with the United States in Manaus on Sunday. Already reeling from a crushing 4-0 defeat to Germany in their opener, Portugal face almost certain elimination if they lose to US. But their preparation for the game could not be going much worse.

Although the Portugal camp insist the Real Madrid forward is fit, Ronaldo has been seen sporting an ice pack on his knee at training sessions and leaving early as his team-mates continued to train. But fellow forward Helder Postiga was adamant that too much is being read into an ice pack. "I personally think that the Cristiano Ronaldo talk is a bit too much so I imagine how he must be feeling about that," Postiga said. "But regarding his physical condition, he's been training at his maximum and if it's not listed in the clinical information of the Portuguese (football) federation it's because he's fit to play."

The US are not without problems of their own as striker Jozy Altidore is out of the game due to a hamstring injury, although US Soccer believe he could be available later on in the tournament. There is better news when it comes to Clint Dempsey, the opening goalscorer against Ghana who broke his nose in that match. He is likely to line up against Portugal wearing a protective face mask. Centre-back Matt Besler, who like Altidore had to come off in the first half against Ghana due to a hamstring problem, is another who should be fit to play.

Russia bar Belgium's path to last 16: Having come from behind to beat Algeria in their opening game, Belgium can reach the World Cup knockout phase by beating Russia at Rio de Janeiro's fabled Maracana. Marc Wilmots's 'golden generation' looked destined to make a meek entrance into the tournament after falling behind to a Sofiane Feghouli penalty in Belo Horizonte on Tuesday, but late goals from substitutes Marouane Fellaini and Dries Mertens got them off to a winning start.

With Russia having been held 1-1 by South Korea in their Group H opener, the last 16 is already within sight for Belgium, who are seen as dark horses to win the tournament after going through qualifying unbeaten. Belgium centre-back Nicolas Lombaerts, who plays for Russian side Zenit Saint-Petersburg, knows better than most what to expect from Fabio Capello's side, and he expects his team-mates to have a physical edge. "Capello places lots of importance on organisation," said the 29-year-old, whose side are appearing at a first major tournament since 2002. "We'll have to pay attention on the turnovers. Russia are not very physical. Our size should be an advantage. They've only got two players taller than six foot (1.85 metres). They'll try to hurt us by keeping the ball on the ground."

Russia needed a 74th-minute goal from Aleksandr Kerzhakov to rescue a point against South Korea after goalkeeper Igor Akinfeev's blunder had allowed Lee Keun-Ho to break the deadlock. It was a low-key opening for a team who pipped Cristiano Ronaldo's Portugal to an automatic berth in European qualifying, but Spartak Moscow midfielder Denis Glushakov has urged his side to put it behind them.

Algeria seek points against Korea: Coach Vahid Halilhodzic has told Algeria now is not the time for tears ahead of Sunday's date with South Korea where defeat will spell yet another premature ending to a World Cup campaign. The Algerians, desperate to end a seven-match World Cup winless run, are pointless and bottom after a 2-1 loss to Group H favourites Belgium.

With the notable exception of their stunning 1982 upset of Germany aside, the story of their World Cup experiences does not make happy reading for the proud Algerians. The north Africans have never made it past the first round, and Sofiane Feghouli's penalty against Belgium was their first goal in the competition in 28 years. With the stakes high, Bosnian-born Halilhodzic told his men to man up.

 "Now is not the time for crying, this match is decisive," the 62-year-old noted disciplinarian said.

Victory meanwhile in Porto Alegre for South Korea would put them on the verge of qualifying. Pacy Korea produced a solid debut in Friday's 1-1 draw with Russia, a performance that gave coach Hong Myung-Bo's team encouragement after a lacklustre build-up. Korean defender Park Joo-ho is predicting a tight tussle. "I don't think either team will have a lot of attacking chances," he said. "If we can score on the chances that we do get, we should have a good shot at winning."