Chelsea have agreed an 18-month loan deal with the La Liga giants for the Spain international.
Morata, who arrived Spain on Saturday evening, will undergo a medical with Atletico on Sunday.
The 26-year-old could make his debut against Real Betis next Sunday in the La Liga fixture.
Speaking ahead of his medical on Sunday, Morata was quoted by Metro UK as telling reporters:
“I’m very happy for this stage, I have been waiting for days, I want everything to be completed and to start training with my teammates.
“The people who have always been with me know how I feel and how I will feel tomorrow and how the last days have been, I am very happy.
“People have their thoughts, but I know what I have to do, I started playing at Atleti and people who know where I come from know my story and what this means to me.
“The past is the past and cannot be changed and I am very proud of that and I hope it will be finished tomorrow.”
