Chelsea could be without midfielder Danny Drinkwater for another month as he recovers from his latest injury.
The £35million deadlne day signing from Leicester City had already missed the first three matches of the Premier League season with a thigh injury.
And now the England international will miss another few weeks after picking up a calf problem in training last Sunday.
Chelsea manager Antonio Conte said: ‘He has a muscular problem in his calf. I think it’s very difficult to see him before the international break [at the start of October].
‘He needs time to recover. It’s a pity because he was starting to work and to improve his physical conditions. Now we have to move all these situations.
‘And in two, three weeks, four weeks, I don’t know.’
Drinkwater has yet to make his Chelsea debut having been forced out of Tuesday night’s 6-0 win over Qarabag in the Champions League.
The Blues face Arsenal in a London derby at Stamford Bridge on Sunday and will also be without Eden Hazard, although the Belgian playmaker is nearing full fitness.
Conte will have defender Gary Cahill available for selection again following the three-match suspension for his sending off on the opening day against Burnley.