The 2011-12 champions have spent over €116 million in the transfer market so far this summer, with Fernandinho, Jesus Navas, Alvaro Negredo and Stevan Jovetic all arriving at the Etihad Stadium.
But the Blues star, who was signed by Chelsea in the year Roman Abramovich bought the club, insists that money is not the key to glory.
| TRANSFER TALK
|2/1||Chelsea are 2/1 favourites with BetVictor to win the Premier League
"Yes, City have huge competition for every place. They have a new manager, new expectations and new motivations - and, if they build a team, they will be a tough opponent and rival for us in the Champions League and for the Premier League title but so will Manchester United. So will Arsenal, Tottenham and Liverpool."
The 31-year-old did acknowledge, however, that City's spending will make them a dangerous rival for his side in 2013-14.
"Manchester City have spent money to challenge. That's the reality of the situation," Cech continued, "so, at Chelsea, we know it's going to be a tough season but we're here as well and working hard to be ready for the challenge.
"We'll try our best to win the league. Our aim is to do the very best we can. We know what our objectives and targets are and will go game-by-game and try to win everything we can and then see."