N’Golo Kante has yet to recover from a knee twist, while Mateo Kovacic is still treated for a hamstring injury.
With Ben Chilwell absent with knee ligament damage, Thomas Tuchel may have to reshuffle his squad – especially as he’s gearing up for the busy Christmas and New Years schedule.
Chelsea face matches every four days over the next month, with the final matches in the Champions League groups and the Carabao Cup quarter-finals also scheduled for December.
Romelu Lukaku’s return from an ankle injury is a welcome boost, but Tuchel is still managing the Belgian’s minutes after fearing he might be mentally and physically fatigued at the start of the season.
The Chelsea manager said: “With Romelu it’s pretty easy. It came [against United] and can continue to train. There was no reaction from his injured ankle.
“He’s stayed in training and is ready to improve with minutes and that’s where he is.
“We have players who have doubts, who maybe need a little more time with more exams to reassess the status. They are Reece James, Jorginho and Timo Werner. They all trained with us today, but there will be last minute decisions regarding all three.
But Tuchel insists he is focused on the present – including an improving Watford under Claudio Ranieri.
“It will be a challenge,” he said. “The good thing is that it was a challenge before. We don’t change our routine. We have very close and close communication with the medical department and our fitness department and we try to predict the load.
“We look at the data [to see] where are the players; Who’s Overloaded, Who’s Underloaded, Who’s Chronically Overloaded, Who’s Intensely Overloaded, Underloaded, and from there we see what we need in the next few games.
“We are doing it step by step. If you look at the calendar too far, you can see that there will be some tough weeks ahead.
“That’s why we focus on the details and focus on the next game, and maybe the next two games where we can rely on the predictions because we have fantastic support from everyone.
“It is now up to the players not only to be strong in games and give their all in games, but to take recovery very seriously, [be] very good for recovery, very good for sleeping and having the right food and the right supplements to be able to recover games because the games are intense.
“Our style of play is hopefully intense and has to be intense to have a certain mentality and identity on the pitch. This is what we want and we are not afraid to shoot.
“We have doubts with Reece, Jorgi and Timo Werner tomorrow, we have late decisions, but we trust the whole squad and it’s no secret that we need a full squad to get through weeks like this. “