"There is almost an obligation to win every game when you are at Manchester United. Nothing else is acceptable.
"That is very difficult for most players to live with but believe me when I say that those sort of challenges are attractive to me. I enjoy that pressure. It makes me fight harder.
"I have demonstrated many things in South America already in clubs like Boca Juniors and Corinthians where the expectation is so great from the fans. I have been successful and done well under that sort of pressure and now I want to repeat the experience in England.
"I think I have already shown some of that with West Ham. I loved that experience and it was always going to be a special club to make me leave there. But a club like Manchester United is one of football's superclubs."
