Real Madrid caretaker coach Santiago Solari labelled Isco "special", but said he was unwilling to rush the midfielder back into the fold before he reached peak fitness.
Isco, 26, underwent an operation to treat appendicitis in September and has not started any of Madrid's past three games – all wins since Solari took charge.
Solari praised the Spain international but said the playmaker had work to do to get back to his best.
"We know Isco's quality and how special he is. He is training to get back to peak fitness," he told a news conference on Saturday.
"He had a delicate operation and it's not easy to come out of that, but he is training with the group.
"All of us who have been footballers know that you have to keep training to get back to your best."
Isco being out has opened up chances for the likes of Dani Ceballos, who has started in two of the last three matches, and Vinícius Junior to make their marks on the first team.
Coupled with the change to Solari as manager, which took place following a humiliating 5-1 loss at the hand of rivals Barcelona, Madrid have hit their stride in the last three outings.
Los Blancos have scored 11 goals and are yet to concede in Solari's time in charge, a drastic turnaround for the club following Julen Lopetegui's failed tenure as manager.
Those matches included wins in the Copa del Rey over Melilla and in the Champions League over Viktoria Plzen, and though those two sides were overmatched the three-game run also included a 2-0 victory over Valladolid in La Liga.
Solari's run in charge will continue on Sunday as his side takes on mid-table Celta Vigo ahead of the international break.