Alexis Sanchez says he expected better of himself following his move to Manchester United.
Sanchez joined United from Arsenal in January but has managed just one goal in 10 appearances since arriving at Old Trafford.
The 29-year-old admits he has struggled to adapt to his new life in Manchester after four seasons with the Gunners.
"As I am self-demanding, I expected something better," Sanchez told the Chilean media while on national team duty in Sweden.
"After my arrival at United, it was hard to change everything very quickly. I even hesitated to come here (to Sweden)."
He added: "The change of club was something that was very abrupt - it was the first time I've changed clubs in January - but many things have happened in my life that are difficult."
Chile missed out on qualification for the World Cup in Russia and Sanchez revealed he wanted to miss Saturday's friendly against Sweden in Stockholm before changing his mind after consulting Chile captain Claudio Bravo.
"I had asked permission to miss these games, but then I thought better and spoke with Claudio and told him that we should all be united," he said.