Maurizio Sarri believes Chelsea missed the movement of Pedro in the sides goalless draw with West Ham.
The Blues dropped their first points of the Premier League campaign away to their city rivals at London Stadium despite enjoying 71 per cent of the possession.
Eden Hazard, Willian and Olivier Giroud all failed to find the net and second-half substitute Alvaro Morata came close but was denied by the impressive Lukasz Fabianski from close range.
Chelsea were without Pedro after the Spaniard suffered a shoulder injury in Thursdays victory over PAOK Salonika and Sarri hopes he makes a speedy recovery.
Antonio Rudiger was forced off with an injury in the 69th minute versus the Hammers but Sarri is confident that the problem is not serious.
I want to speak with the doctor, the Italian said.
I think nothing serious. Maybe three or four days.