BRASILIA, Brazil (AP) -- Argentina winger Angel di Maria is in doubt for the World Cup semifinals with a right thigh injury, possibly robbing the team of one of its best attacking threats.
Di Maria was substituted in the first half of Argentina's 1-0 win over Belgium in the quarterfinals on Saturday. Argentina coach Alejandro Sabella said the Real Madrid midfielder would have medical tests on Sunday to discover the extent of the injury.
''I hope that it won't be too (bad) in the case of Angel because Angel is vital to us,'' Sabella said.
The coach gave no other details of the injury.
Argentina will play either the Netherlands or Costa Rica on Wednesday in the semifinals as it seeks its first World Cup title since Diego Maradona led the country to victory in 1986.
Di Maria limped off in the 33rd minute against Belgium at Estadio Nacional after he had helped set up Gonzalo Higuain's decisive early goal for Argentina. Di Maria also scored the winner against Switzerland in the second round.
On Saturday, he tried to play through the injury but couldn't, soon dropping to the ground near the center of the field with his hands over his face.
As Argentina labored through the group stage, Di Maria and Lionel Messi were its two best forwards and will be relied on to provide much of the attacking threat in the next round, if Di Maria makes it.
''He's a key player in this project,'' Higuain said. ''I'm really sorry. But we hope that he will be ready as soon as possible because we know what he does for the team.''