Ballack said: "The top teams cannot afford to relax and there is no room for error. It is a good season for the fans because it is very close and open.
"We hope to take our chance if they slip up, but we have to wait. Maybe, this season, the big games will make the difference.
"The title could be decided at Stamford Bridge and when these games come, we hope to have one or two important players back."