The 21-year-old has joined the capital outfit on loan from Granada and is confident that he can 'fulfil his objectives' at Rayo.
"I come here to fulfil my objectives and grow as a professional," Inside Spanish football quotes Fatau as saying.
"It is a dream for me to arrive at Rayo because I have a lot of faith in Paco [Jemez]. I think I can learn a lot from him. Rayo were the team at the top of my list even though others were interested."
Fatau made nine appearances for Granada last season.