The defender will miss the weekend trip to Leicester, for which Raheem Sterling is a doubt due to a muscle issue.
Already absent for the match were Thiago Silva, N’Golo Kante, Edouard Mendy, Armando Broja and Mason Mount.
A question mark hangs over Cesar Azpilicueta’s involvement while Pierre-Emerick Aubameyang is expected to fail his bid to be fit.
Here is your latest update of Chelsea injuries and return dates…
Silva was initially ruled out for as many as six weeks when hit by a knee injury late last month, setting him up for a return after the March international break.
And Potter sounded a warning to any fans hoping for a quick comeback when, on Friday, he suggested he will not take risks with the veteran with the “most important thing being getting him back injury free”.
Graham Potter confirmed on Friday that Chelsea defender James had been struck down by illness, causing him to miss training and subsequently the match at Leicester.
It means he will have played in just four of the last 18 Premier League games after the King Power Stadium clash, although, all being well, he should be back to face Everton a week later.
An abdominal injury put Mount on the sidelines last week and Potter outlined plans to keep him back from playing for a little while longer, with a return against Everton possible.
The Chelsea boss said: “He probably needs a little bit more time. He is happy around the place and wants to help the team, that is normal with Mason. He wants the team to win, be injury free, and play football.”
Kante is back in training but not available for the Leicester game, having not played since August due to a hamstring issue.
Next weekend’s Everton match has been described as a “maybe” by the midfielder’s manager.
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A back injury has ruled Aubameyang out of facing Leicester.
However, the issue was only deemed “slight” by Potter on Friday, raising hopes he will be back for the following match.
Chelsea continue to monitor Azpilicueta’s return from a concussion against Southampton some three weeks ago.
There are hopes he will be fit to face Leicester but the club have not confirmed his status, the defender having been pictured in training during the build-up.
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It has been some time since Chelsea fans witnessed Mendy in between the posts and he will continue to be unavailable for the trip to Leicester.
However, the goalkeeper is training and could feature in a squad in the coming weeks.
Young striker Broja’s season is over following a serious knee injury suffered in a mid-season friendly.
Surgery was required and the Albanian is now focused on his rehabilitation ahead of the coming pre-season.