Also from the article above...
https://theathletic.com/news/chelsea-reece-james-injury-latest/IZlLqIMxHRMy
Hakim Ziyech hasn’t featured since suffering a hamstring injury against Leeds and The Athletic understands the West Ham game is expected to come too soon for him to feature.
Ziyech joined in training with the main group for the first time on Friday, but the fixture at Arsenal on Boxing Day is looking more likely for him to make a comeback.
There is far more confidence, however, over Callum Hudson-Odoi, who has also been missing since injuring a hamstring in training a fortnight ago.
The England winger also joined in Friday’s training session and is further advanced in his return to full fitness. Given the busy festive schedule, however, he will probably not be risked from the start.