Zinedine Zidane wants Isco at Real Madrid for "his whole life" and insists claims the player could leave at the end of this season are false.
But as their title defence has stumbled domestically this term, the 25-year-old has found starts harder to come by.
Isco was an unused substitute as Madrid slumped to a 3-0 Clasico loss against Barcelona before Christmas, while last weekend's goalscoring contribution to the 2-2 draw at Levante also came from the bench.
The likes of Chelsea, Manchester City and Liverpool have been linked with a move for the former Malaga man but speaking ahead of Saturday's match against Real Sociedad, Madrid's head coach categorically denied he could leave.
"I'm glad you've asked me. I was asked before [during the January transfer window] why weren't we going to sign anyone," Zidane told reporters.
"I said I've always believed in my team and I will do until the very end. When I start something I get involved, I believe where I'm going, what I should be doing and I back the people I'm working with.
"Isco's one of them. He a very good footballer. He's proven that in the past and will do that again
"I want Isco [in my team] and I want him to spend his whole life here.
"It's a lie that I want Isco to be sold in the summer. Hopefully we won't hear any more of this."
66 - Isco Alarcon has played more La Liga games than any other Real Madrid player under Zinedine Zidane (44 starts, 17 goals and 16 assists). Essential. pic.twitter.com/deIrAx7wqh— OptaJose (@OptaJose) February 7, 2018
Nevertheless, Zidane was keen to point out that his backing for Isco did not mean a guaranteed run of starts, given the competition for places in his Madrid squad.
"There's 25 of us. Everyone is important," he said. "I get asked this question by you, by somebody else – why Isco? Why [Marco] Asensio?
"The most important thing for me is the team. Isco won't play every game between now and the end of the season but he's part of the squad.
"I have to pick a team. There are many games.
"I get asked about Isco and I'm pretty sure I'll get asked about Asensio and [Dani] Ceballos and players who might play less than their team-mates
"These questions are common. I'm the one with a tough decision to make."
Isco has started 14 games and come on four more times in La Liga this season, scoring five times, and started all but one of their Champions League group games.