Chelsea manager Maurizio Sarri insists that his side cannot win the Premier League title this season.
The Blues are one of three teams still unbeaten in the top-flight, though they sit four points behind Manchester City.
Chelsea have won eight games and drawn four, while Liverpool have won nine and drawn three, and City have won 10 and drawn two.
However, Sarri does not think that his side are equipped to challenge champions City, insisting that there is a "mental problem" at the club as they prepare for a London derby clash with fierce rivals Tottenham.
“At the moment, no we cannot catch them,” he told a press conference.
“For me, they are stronger than us at the moment. We have to work, we have to work very hard just to try to recover the gap. But, at the moment, the gap is still there.
“I think it’s a mental problem. In the last three matches, we had problems with the approach to the match.
“Not only that, because we had some problems also in the beginning of the second half. So we have to be careful. We have to be focused on this problem.
“For sure, it’s not a physical problem because, in the last part of the match, we ran a lot, I think. It’s not a physical problem. It’s a mental problem. We have some difficulties to enter into the match.
“It’s not a tactical problem. Because in the first 15 minutes in the last three matches, the problem was the opponents were more aggressive, more determined than us. So it’s not a tactical or physical problem. We have to approach the match in a different way, for application and determination.”
Sarri and the Blues were boosted by the news of N'Golo Kante's new contract, the midfielder penning a new five-year contract on Friday.
“N’Golo, for us, is not just an important player," he added. "He’s a ‘determinate’ player for us. So I’m really happy with the new contract. Clearly very pleased for him. And it’s a very important news, I think.
“I know that David Luiz told something about him, that he doesn’t want to pay the bill in the restaurant. So he has a flaw like everybody. But I think he is a really professional player, very professional on the pitch and off the pitch.
“He’s very important for us in the defensive phase, but he is improving in the offensive movements. Now he has to improve in the last 25m. He can score more.”