Isco said he felt “alive” after his first career hat-trick helped Spain thrash Argentina 6-1 and took a swipe at his club coach Zinedine Zidane.
The Real Madrid playmaker has seen his club football limited in spells under Zidane this season.
However, Isco produced a superb display against Argentina, whose captain Lionel Messi again watched from the stands at the Wanda Metropolitano because of fitness concerns.
Spain had drawn 1-1 against Germany last week and have now extended their unbeaten run under coach Julen Lopetegui to 18 matches.
“In Madrid, I don’t have the confidence a player needs, ” Isco said in a post-match interview, as quoted by Marca.
“The matches with the national team give me life. Here, I have the confidence of the coach.
“I want to show that I’m a good player. Lopetegui shows me confidence with the minutes he gives me.
“Maybe I’m the problem in Madrid. I don’t know how to win Zidane’s confidence.”