Head coach Mauricio Pochettino has confirmed that Ben Chilwell faces a period on the sidelines with a hamstring injury.
After starting a number of games among the replacements, Chilwell returned to the team for Wednesday's EFL Cup third-round tie against Brighton & Hove Albion.
However, during the closing stages of the 1-0 win at Stamford Bridge, the left-sided player was forced to come off courtesy of an issue with his hamstring.
A report in the Evening Standard has indicated that the England international faces the prospect of a month on the sidelines.
While Pochettino has hinted that Chilwell will not return in the short term, he refused to confirm a timeframe for the player's recovery.
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Speaking to reporters, the Argentine said: "It was in the last minute of the game. Yes, we are really sad about the news over Ben.
"It is difficult to know now (how long). It is less than two days since it happened. We need to assess in the next few days and the doctor will tell us so that the club can communicate."
Nevertheless, there was positive news regarding Carney Chukwuemeka - who has been absent since the middle of August with a knee injury - and Noni Madueke who sustained a muscle problem during his time with England Under-21s earlier this month.
He added: "We hope that maybe Carney and, of course, Noni, also after his injury when he came back from the national team. He is getting ready and working hard. We hope that, maybe, these two players will be available for selection on Monday."
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There have also been reports regarding Reece James, who has not featured since the opening weekend because of a hamstring injury, with it being suggested that the club captain could return against Arsenal after the international break.
Although Pochettino has dismissed the possibility of James featuring against Fulham, he refused to rule the right-back from returning versus Burnley on October 7.
Pochettino said: "For Monday, I don't believe. Maybe the week after, we will see. We need to assess him, but we cannot confirm at the moment."
Chelsea head into the game with their West London neighbours having accumulated just five points from their opening six matches in the Premier League.
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