Pablo Zabaleta has told IBTimes UK that Chelsea made the perfect signings during the summer transfer window, but refuses to admit that Manchester City failed to do likewise.
Manuel Pellegrini tried to solve his defensive concerns last season by signing goalkeeper Willy Caballero, Arsenal right-back Bacary Sagna and Porto duo Fernando and Eliaquim Mangala.
However City missed out on Radamel Falcao, while letting Alvaro Negredo leave the team on loan to Valencia.
The four new signings are yet to make the impact expected at the Etihad Stadium, and Pellegrini's side have had a difficult start to the campaign with Chelsea already six points above them in the Premier League.
City won both the Premier League and the Capital One Cup last season, but Chelsea look to have overtaken them with a raft of key signings, including Diego Costa and Cesc Fabregas, who have quickly settled into the Premier League pace.
When asked by IBTimes UK whether the summer transfer business of both sides has made a difference so far this season, Zabaleta said: "I steer clear of giving my opinion on that."
"The club [Manchester City] relies on professionals to decide the signings. Chelsea have signed good players who are working well, especially Cesc [Fabregas], who already knows the league very well. But there is still a long way in the league to already think that Chelsea will be the champions."
Asked about the reasons of City's stuttering start, Zabaleta said: "I am sure we can improve regarding what this team can give, because of the quality players we have.
"But we have to keep working on things that we are not doing as well as last season to get that. Last season we were much more aggressive and we scored goals much more easily.
"Every season after a World Cup the players are physically more tired. When you do not rest enough and you don't' do a good pre-season it is difficult. Many of us arrived late and maybe you are not seeing the best shape from us. But the only way to get it back is to keep working."
Meanwhile, the Argentinian praises his compatriot Sergio Aguero after the striker scored against Manchester United, his tenth goal in 10 Premier League games.
"Kun is a great moment of form. For us to have a player who scored goals in every game gives us the ability to be stronger. If he keeps injury free he is a player that is going to give a lot, because last season the injuries didn't let him be as consistent."