Neville suggests that an injury to either Diego Costa or Eden Hazard are the only instances in which the Premier League title will not be returning to Stamford Bridge.
"I didn't think they would be champions at the start of the season," he said on Sky Sports.
"I'm still not sure, I wouldn't fully trust any of them yet, but they do like they are producing the type (champions) performances.
"The Southampton away one, that's the one where I thought, that's a championship winning performance. But it is too early in the season to hand them the title.
"You still have to have doubts over them through the fact, for instance, if you got an injury to Eden Hazard, an injury to Diego Costa.
"You have to throw in the doubts that exist. They are such important players."