Mexico defender Diego Reyes will miss the World Cup after failing to recover from a hamstring injury.
The Porto centre-back sat out both friendly matches with Scotland and Denmark this month, but head coach Juan Carlos Osorio was keen to wait until as late as possible to give him the chance to prove his fitness.
However, a statement from the Mexican Football Federation has confirmed Reyes "was not able to satisfactorily complete his recovery" and will play no part in the finals in Russia.
He will be replaced in the squad by Pachuca's versatile 22-year-old Erick Gutierrez.
Reyes struggled with fitness problems throughout 2017-18 but was still expected to be a key part of Osorio's first-team plans.
Mexico were already without defender Nestor Araujo, who failed to recover from a knee injury in time for the tournament.
El Tri begin their campaign against holders Germany in Moscow on Sunday.