The 22-year-old joined United from Mexican side Guadalajara in April this year.
“United’s interest in me came as a complete surprise,” he told the Sun.
“Initially, I believed it to be pure rumour but now I am here.
“Even when I signed the deal, I was still worried about the question hanging over my work permit.
“At any given moment I could have gone on loan to another European club instead. But United worked the situation very well.
“And though it is complicated to make an early impression at a big club like United, plus it is not easy to adapt to a new country, United helped me through.
“Many people thought Spain or Italy would offer me my best chance in Europe.
“But my dream was to play for United and win the Premier League.”
“I am a rookie in the Premier League. But I am happy so far with my start, my goals and my work-rate.
“United have enormous options up front but Alex Ferguson has given me chances and I’m grateful for that.
“He is a coach with very clear ideas. From the first day he spoke with me and explained what he wanted.
“He insisted there was no need for me to feel anxious or nervous. I think I am fulfilling what he wants.”