As the fourth official raised his board with 54 minutes gone in the Spanish capital, a look of disbelief quickly spread across the face of one Isco Alarcon.
Despite the home side being just a goal to the good, Lopetegui opted to take the opportunity to give youngster Fede Valverde some game time, not that it sat well with one of his more established stars.
Isco slowly trotted off the pitch, before doing something largely out of characted with his usual behaviour.
As the Malaga-born star reached the bench, he blanked Lopetegui, who was stood in his technical area, before raising his hand to his mouth to hide a sly comment from prying eyes.
Only Isco and Lopetegui know what was really said, but with Isco looking furious at having been given the hook, the evidence would appear to point in one direction.