Veteran Uruguay forward Diego Forlan had to sit out Wednesday's training session ahead of the World Cup because of a digestive problem.
The 35-year-old was one of the stars of the last World Cup in South Africa, being awarded the Golden Ball for best player of the tournament.
And with Luis Suarez, who has a knee injury, unlikely to be fit for Saturday's first match against Costa Rica, Forlan is expected to play an important role.
"He woke up with a digestive problem and stayed in the gym. He'll train normally later on," a Uruguay team spokesman told AFP, adding that Forlan's problem was not serious.
With the team set to travel to Fortaleza, where they will play Costa Rica in Group D, on Thursday, they are due to train a second time later on Wednesday.