Liverpool currently top the table with four wins out of four, though Chelsea and Watford are also on 12 points after their perfect starts to the season.
But Sarri, whose Chelsea side have defied expectations and could be a surprise challenger for the title come May, believes it’s still only City and Liverpool who will be fighting for the top prize.
“At the moment I can answer Manchester City or Liverpool,” said Sarri about this season’s title challengers, via Metro.
“We need another step I think to be at the same level. I think so, but I hope not. It’s very difficult. The gap last season was 30 points so I think to go above 30 points in one season is very, very difficult. I think we must improve but we can improve.”
Chelsea have managed to stake out a 100 per cent win rate so far this term, beating Huddersfield Town, Arsenal, Newcastle United and Bournemouth before the international break.
It remains to be seen how they’ll cope with a top Premier League side, discounting Arsenal who are still finding their rhythm under new boss Unai Emery.
But Liverpool and City are the footballing world’s tip for the title, between them, with the Citizens looking as slick as last term and Liverpool an undeniably altogether stronger force than last season with their extensive transfer activity.
Chelsea take on Cardiff at Stamford Bridge on Saturday afternoon, with Sarri looking to become just the fourth manager to win his first five Premier League games after Carlo Ancelotti, Craig Shakespeare and Pep Guardiola.