The Brazilian midfielder was talking after Sane's latest man-of-the-match performance as the young German winger scored his fifth goal of the campaign and claimed two assists in the 5-0 rout over Crystal Palace.
Fernandinho says his team-mate has the talent to keep getting better.
"We all knew Leroy was a great talent from last season," he said. "Last year he showed that and this year he is showing it again.
"In football it is difficult to know what will happen. We hope he can achieve the highest level possible for City and his national team.
"He is young, he has shown his quality. I am happy he is happy. Everyone is happy and I hope he can keep this level as long as possible and keep getting better.."
City can't stop scoring this season and the Blues equalled a record of five goals or more in three successive top flight games for the first time since Blackburn achieved the feat in 1958/59.
Fernandinho believes the Blues are simply taking their chances this campaign rather than squandering opportunities.
"If you compare things with last year where we created so many chances but we didn't score, the difference is this year we are putting those chances away," he said.
"I don't know what has changed, to be honest, I am not a specialist to talk about that, but I am so happy we are scoring goals. This is important because one of the things that can decide the title is goal difference, and we are on the right path in that respect."