Gaya sprained his ankle in Spain training on Monday and has been replaced by Barcelona youngster Alejandro Balde, who must be pinching himself at the unexpected opportunity.
The prognosis for Gaya's recovery has been set at at least ten days meaning he would have definitely missed the matches against Costa Rica and Germany prompting La Roja to make the difficult decision.
Apart from Balde, Barca's Jordi Alba is the only other available left-back in the squad, while Manchester City's Aymeric Laporte filled in for an hour in Thursday's friendly win over Jordan.
Balde, who grew up in the La Masia Academy from the age of eight, has grown from strength to strength after being handed his first-team debut by Ronald Koeman last season. Such has been his improvement that he has even been Barca manager Xavi Hernandez's preferred choice at left-back ahead of Jordi Alba and Marcos Alonso. Balde has never been capped at senior level for Spain.