Hat-trick hero Isco said it was a relief to play for Spain as he feels Real Madrid coach Zinedine Zidane has no faith in him.
Spain destroyed Argentina, who were without Lionel Messi, 6-1 in a friendly on Tuesday as Isco stole the show with his triple at the Wanda Metropolitano.
The 25-year-old has become a key player under coach Julen Lopetegui and is expected to start at this summer's World Cup in a front three alongside Diego Costa and David Silva.
But Zidane has not shown the same faith in him at Real Madrid, where Isco has often found himself on the bench behind the likes of Marco Asensio and Lucas Vazquez.
"Lopetegui gives me confidence with minutes, with games," Isco said.
"With Madrid I do not have the confidence that a player needs, maybe the problem is me, that I have not won Zidane's confidence with the good players there."
Isco signed a five-year contract with Real in September last year but there would be no shortage of suitors should he decide his future lies elsewhere.
English Premier League pair Manchester City and Tottenham Hotspur are rumoured to be interested in signing Isco.
- 'ENTHUSIASM TO WORK' -
"When you don't play a leading role or have continuity in your club team, the games with the national team give me life," Isco said.
"I have the confidence of the coach here (with Spain), I still have a lot of enthusiasm to work, to improve, to be a starter for my club and in the national team.
"I feel that I'm at the beginning and I want to show that I am a good player."
Isco left the stadium with the match ball under his arm but it was a good night too for Diego Costa, who put his hand up to be Spain's lead striker in Russia by scoring the opening goal.
Costa had been left out by Lopetegui while inactive during his departure from Chelsea to Atletico Madrid but he would appear now to be in pole position up front, ahead of Rodrigo Moreno, Iago Aspas and the out-of-form Alvaro Morata.
"During the nine months I went without being called up by Spain I felt bad," Costa said. "I went six months without playing as you all know, but I knew that if I started playing again I would have a chance of returning, and I'm happy to be here."
Costa had to be taken off after colliding with goalkeeper Sergio Romero for his goal but the striker indicated he would be fit to face Deportivo La Coruna this weekend.
"I think I will be fit to play Sunday," Costa said. "I took a knock, I'll put ice on it and that's all."
Aspas, the leading Spanish scorer this season with 16 goals for Celta Vigo, did his own chances no harm by coming on to score one and set up two more in a flurry of second-half goals.
Thiago Alcantara made it four shortly before the hour-mark after Nicolas Otamendi earlier headed in what turned out to be no more than a consolation for Argentina.
Messi's hamstring strain meant the visitors were without their talisman and after an unconvincing qualifying campaign, Jorge Sampaoli's side have now lost two of their last three games, conceding 10 goals in the process.
This latest defeat in Madrid came on the back of Friday's stodgy 2-0 win over Italy and a 4-2 loss to Nigeria.
"This result means we have to take responsibility and take another look at who will make the final list," Sampaoli said.
"We have to look for the chance to continue working so that these things do not happen to us at the World Cup."
