By FOX Sports staff
Morata was surprised to hear he had been included in Jose Mourinho's first XI and made the most of the opportunity by taking just three minutes to open his account at the Bernabeu.
"I am very proud to be in this squad and play in matches like this," Morata told the club's website.
"I am learning and I am in no hurry. I need to take it step by step".
He added: "I didn't expect to be in the starting XI and when the coach told me it made me extremely happy. To start a match at the Bernabeu and score my first goal here is incredible".
Madrid would soon go up 2-0 in the contest following Morata's effort with Sergio Ramos scoring in the 12th minute and the scene was set for Mourinho to record an easy win in his 100th La Liga game in charge.
However, the game became a much more tight affair following the dismissal of Ramos just six minutes later for two soft bookings in quick succession.
"There are times when this sort of thing happens, that's life and I'm happy because the team won," Morata said of the red card shown to team-mate Ramos.
"We know the criteria that the referees follow and that it is up to them. It is always difficult to play with a man less and Rayo do it very well. They are a great team and they lacked a little punch. They will be up their fighting for a place in Europe".
Real next play away to Deportivo on Saturday.