"The truth is that I've been suffering with my knee since 2013. I had a lot of problems that season, and small episodes after that with my knee, something always was bothering me", says Sergio.
"I talked to the Manchester City doctors this year and we said we're going to wait because we were still in the Champions League.
"It did not improve so we talked with Pep and he was very supportive. He told me to stay calm and to take care of my knee.
"So, after we were eliminated from the Champions League, I talked to the doctors, I told them that I wanted to be ready for the World Cup so the best option was to have surgery.
"After five years, I feel no pain and my knee feels like new. Having problems with my meniscus caused an overload in the hamstring, the quadriceps, the gluteus now I feel different because my knee is cured.
"For example, for the last five years I couldn't flex my knee all the way and now I can do it. It's a total relief."