Lionel Messi came off the pitch in the 73rd minute of his last club match before the World Cup on Sunday, but Inter Miami coach Guillermo Hoyos said he thought the Argentine was just fatigued after playing on a heavy pitch.
The eight-time Ballon d'Or winner was substituted after clutching the back of his thigh in the wake of one of his trademark free kicks during Inter's 6-4 win over the Philadelphia Union in Miami.
"We don't have a medical report on that yet, but we will have one shortly," Hoyos told reporters when asked why the talismanic forward was taken off.
"He was genuinely suffering from fatigue in that regard; it is indeed fatigue. He was tired, the pitch was heavy and when in doubt, the standard approach is always to ensure you don't take any risks."
Major League Soccer is now taking a mid-season break for the World Cup, which will be co-hosted by the United States, Canada and Mexico from June 11 to July 19.
Argentina coach Lionel Scaloni announced a 55-man squad, including Messi, on May 11. He will need to reduce it to 26 before FIFA's June 1 deadline.
Messi was highly influential as Argentina won the World Cup for a third time in Qatar four years ago. They open their title defence against Algeria in Kansas City on June 16.