Hakim Ziyech was forced off with a shoulder injury in the first half of the UEFA Super Cup clash against Villarreal.
The winger was marking Juan Foyth and appeared to come down awkwardly in an innocuous collision that caused an awkward landing.
The Moroccan international immediately clutched his shoulder before receiving treatment on the pitch while in visible discomfort. The former Ajax star appeared to use his shirt to cradle his arm's weight when he was replaced by Christian Pulisic.
Ziyech took his place on the bench in the second half with the addition of a sling for his right arm.
He had continued his impressive pre-season form and gave the Blues a deserved lead over the yellow submarine. Kai Havertz found his teammate with an incisive ball from the left and Ziyech ghosted in from the opposite flank to produce a calm finish.
The substitution will leave Thomas Tuchel sweating just three days away from the Blues' opening Premier League game against Crystal Palace.
Ziyech had been involved in the entirety of Tuchel's pre-season programme and had benefitted immensely from it. The 28-year-old bagged a hat-trick in a behind closed doors friendly against Peterborough, impressed against Arsenal despite his miss and bagged a brace in a standout performance against Tottenham.
The Chelsea star seemed destined to start at Stamford Bridge for the visit of the Eagles but now seems unlikely to do so.
