The 26-year old came off the bench to make a scoring start to the season in City's 4-0 win over Newcastle United on Monday, following a frustrating 2012/13 campaign when he only netted two Premier League goals.
Manuel Pellegrini's midfield has been boosted by the arrivals of Jesus Navas and Fernandinho this summer, but Nasri says signings will help him to raise his game.
"The competition for places at City doesn't frighten me, it makes me better," he told The Sun.
"I'm full of desire. I want to go to the World Cup and show everyone the real Samir Nasri.
"I've trained with this in mind. I'm much sharper and I feel better.
"I have matured a great deal. I lost my way a bit last season, but I have found myself once again."