Maurizio Sarri believes challenging for the Premier League remains a step too far for Chelsea despite their 100 per cent record in the opening weeks of the 2018-19 season.
Sarri arrived at Stamford Bridge in July and has hit the ground running, winning all four of their league matches prior to the international break.
Only Liverpool and Watford have matched Chelsea's impressive start, with champions Manchester City two points behind having drawn with Wolves last month.
But Sarri does not see his side battling for the title at the end of the season, instead thinking Liverpool and City will be the two teams vying for silverware.
"At the moment, I can only see City or Liverpool [winning it], at the moment," he told a media conference.
"We need another step to be at the same level. I think [it is too soon], but I hope not!
"It is very difficult to recover 30 points in one season, very difficult.
"We need to improve. My feeling is that we are not a very solid team in the defensive phase, we need to improve and we can, my feeling during the training is that this team can improve."
Chelsea could welcome Cesc Fabregas back to the matchday squad against Cardiff City on Saturday, the Spanish midfielder having missed the start of the campaign with a knee injury.
Fabregas is likely to only be fit for a place on the bench, though, and could replace Ruben Loftus-Cheek, who picked up an injury on international duty with England.
"The best news is Fabregas, he is very well, he was training with the team during the week so now he only has to improve his physical condition," added the Italian. "I think in one week he will be ready to play.
"I think that at the moment Fabregas can be on the bench, but I want to speak to him, I think maybe it is better to have two days of training.
"Yesterday [Thursday] there were problems with fever for Emerson [Palmieri] and [Davide] Zappacosta, and a little problem after the match with the national team for Loftus-Cheek.
"I don't know the situation, I have to speak to the doctor, I don't know if he will be able to play."