Mourinho has been working with limited numbers and several star names are still away on their summer breaks following the tournament.
Arda Guler was one of the first players back in action at Valdebebas, after Turkey's group stage exit in North America, as he pushes for a starting spot in Mourinho's XI in the weeks ahead.
Ahead of their preseason tour of Europe, he is confident of making an impression, with Jude Bellingham, Kylian Mbappe and Aurelien Tchouameni all still absent.
"It's a great opportunity to work with a legend like Mourinho. He and his team explain everything very clearly and are very sincere off the pitch.
"In preseason, the most important thing is to work on the physical aspect, but also listen to what Mourinho asks of us, so we can do well on the field."
Real Madrid take on Leganes on July 28 before taking on Fiorentina, Ferencvaros and Deportivo la Coruna in August.