Ronald Koeman was missing his two first-choice centre banks for the game in Ronald Araujo and Gerard Pique, so opted for the combination of Oscar Mingueza and Umtiti while leaving Clement Lenglet on the bench.
His decision to bet on Umtiti backfired, just as it did against Granada in the previous round of the Copa when the Frenchman made errors that led directly to goals.
The balance of the game was fine initially, until Kounde emerged. Also from France, the 22 year-old scored a stunning solo effort to put Sevilla into the lead inside the opening half-hour, beating Umtiti directly before finishing coolly.
At the other end of the pitch, Kounde was similarly effective, pressing well and marshalling Lionel Messi. He played with a competence and confidence that sets him apart from most.