Warnock disclosed this ahead of his side's Premier League clash against the Blues on Saturday afternoon.
Asked which teams are in title contention, Sarri said: "At the moment I can answer City or Liverpool, at the moment".
"We need another step to be at the same level. It's very hard. The gap was 30 points at the beginning of the season".
"This was only because after the first season the players understood the difficulty of this kind of match".
Things don't get much easier with this trip.
Midfielder Ampadu, who celebrates his 18th birthday today, shone for Wales against the Republic of Ireland and Denmark during the worldwide break.
Speaking in an interview with BBC Sport, Lawrenson said: "Like Liverpool and Watford, Chelsea have got a 100 per cent record from their first four league games and I see that ideal start continuing here".
"So we changed our worst year for a long time into the best year in the history of this club".
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'In a few days, one week, he will be ready to play. It'll be interesting to see how we cope at a packed Stamford Bridge.
Chelsea are battling to return to the Champions League this season after finishing outside the top four last term.
When and what time is the Premier League match between Chelsea vs Cardiff City?
On paper, this game looks like a straightforward win for Chelsea.
The Blues will absolutely want to make Sarri a flawless five-for-five in the Premier League, but the task could be more hard than many may anticipate.
Since the start of the 2016-17 season, Chelsea's Marcos Alonso has been directly involved in more league goals than any other defender in Europe's big five leagues (14 goals, 7 assists). Chelsea have been excellent going forward.