The young attacker made his senior debut last season and ended the year as U19 Euro champions with Spain.
Now back with Betis for preseason, Diao said: “I was lucky enough to fulfill my dream, I was able to debut and stay with them. The finishing touch was the National Team.
“I have an environment that is always by my side and advises me the best possible way. This gives me happiness, I cannot thank them with words."
He continued: “The club needs a guaranteed squad with players of the highest level. It is important to compete in the Liga and the Copa del Rey.
"Goals? I want to take the next step in my career, be important and win a title this year.”
He also insisted on the influence of coach Manuel Pellegrini: “I really want to show why I am here. We are all very grateful for the coach's work. Position? I started playing behind when I was little and I moved forward.
“I like to play as a forward and as a winger.”