The west Londoners have enjoyed a superb start to the season, claiming 22 points from a possible 24 to lead Manchester United by four points at the top of table.
Roberto Di Matteo’s men kept their impressive run going with a thrilling victory at Tottenham Hotspur on Saturday – but Mata believes it is still too early to say whether the Blues will be able to continue their top form.
“The next two months will decide if this is a genuine title challenge,” said Mata. “It’s always like that in November and December.
“There are a lot of games and you have to keep fighting for the title in those two months. For me it’s the most important part of the season.”
Meanwhile, Chelsea goalkeeper Petr Cech also refused to get carried away with his side’s eye-catching start to the season, which also includes a win at Arsenal.
“We have made many good starts in the time I have been here but we started slowly the first two games this season. We seem to get better as the team gets to know each other,” said Cech.
“Now we have played two tough away games at Arsenal and Spurs and we got six points which is a huge advantage, but now we await the game against Manchester United at home because that will be a another big test.”
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