Spain defender Asier del Horno is a major doubt for the World Cup finals after suffering an ankle injury.
The Chelsea left-back picked up a knock during a practice match on Wednesday and the results of a scan on the problem were less than optimistic.
National team doctor Genaro Borras said: "He injured himself in the game and he was still suffering this morning so we did a scan.
"He has damaged the area around the Achilles tendon in his left ankle. It is a small injury but by way of a precaution he will do nothing until Monday when we will see how it has healed.
"We will do further tests on Tuesday. We have to be realistic. I hope it heals but I have my doubts. It could put his participation in the finals in doubt."
However, there was better news about Real Madrid defender Michel Salgado, who will be able to return to training next week after tests showed his hamstring injury is not as serious as initially feared.