The Ivory Coast international completed a blockbuster transfer move from RB Leipzig to Madrid last month, as part of a deal that could eventually reach £120M (€140M) if certain add-ons are triggered, as Leipzig made a huge profit on the €20M they paid for him 12 months ago.
The 19-year-old played a reduced role in preseason before being handed a full debut off the bench in Los Blancos season-opening win at Espanyol.
Kylian Mbappe, Vinicius Junior and Arda Guler all started in Catalonia, but Diomande is determined to force himself into Mourinho's starting plans.
"There's no bigger club than Real Madrid. They spent a lot of money on me, but I don't feel any pressure. Why should I be afraid? I'm going to do what I can on the pitch, and God will do the rest.
"Mourinho got up at 5 a.m. to talk to me. That means I'm important. When Real Madrid calls you, you can't say no, so I said, 'If they want me, I'll be there'.
"I'm happy to work with him because he's the best. I can learn a lot from him; he's the right coach to continue my development. I'm ready to die for him."