Sevilla head coach Jorge Sampaoli felt his side could have beaten Leicester by a greater margin as he acknowledged the contribution made by goalkeeper Kasper Schmeichel.
The Primera Division side claimed a 2-1 win with goals from Pablo Sarabia (25) and Joaquin Correa (62), as Jamie Vardy scored for the Foxes (73).
Schmeichel was called on to a make a significant number of saves throughout the tie, not least from Correa from the penalty spot on 14 minutes after captain Wes Morgan had fouled the Sevilla attacker.
After the match, Sampaoli said: "We dominated and had to contend with Schmeichel at a high level. If it were not for him the story would be different. He was very good.
"I am happy because the gulf in the match was very large. But we did not have the luck to capitalise."
He added: "We were far superior in the development of the game, with 10 clear, scoring chances. They did very little but succeeded in the end. I think we deserved a bit more.
"We had all sorts of chances but hit the post and crossbar. Our opponents only had a few chances, but now we have to go to Leicester for the win. We wanted to confuse our opponents a bit by getting our forwards to change positions.
"Still, it was possible to create many chances against a team that sat very deep. That's not easy."
Sampaoli concluded: "But playing this way, if we do not concede in England then we will qualify. We must not disregard what was a good performance [by Sevilla].
"The unique approach of the opponent [playing on the counter] ended in a goal. These teams live off this. We live embittered by the narrow result."