Dutch captain and all-time top scorer Robin van Persie is in doubt for the World Cup semifinal against Argentina after succumbing to a stomach problem.
Van Persie trained separately on Tuesday with defender Daryl Janmaat and coach Louis van Gaal said both were suffering "stomach and intestinal problems."
Van Gaal said he would not rush into deciding whether Van Persie is fit to play at Sao Paulo's Itaquerao Stadium against the Lionel Messi-led Argentina.
"I have to make a decision tomorrow. I'm not going to do that today. We have more than a day," Van Gaal said. "Van Persie is a very important player for us."
Van Persie scored three times in the first two Dutch matches of the World Cup, including a spectacular diving header against defending champion Spain that was instantly hailed as one of the goals of the tournament.
But the Manchester United striker has struggled to hit the same rich vein of form since being suspended for the Netherlands' last Group B match after picking up two yellow cards.
Against Argentina, the prolific striker is looking to break a remarkable drought for a player of his caliber — he has never scored in the knockout stage of a major tournament.
In potential good news for the Dutch, midfield enforcer Nigel de Jong trained Tuesday and could play against Argentina, depending on how he feels Wednesday.
There were fears De Jong's World Cup was over when he limped off early in the first half of the second-round match against Mexico and tests confirmed the day after the come-from-behind 2-1 victory that he had torn a groin muscle. The team said he was likely out for two to four weeks, but De Jong battled back.