U.S. men's national team star Christian Pulisic suffered an injury in warmups ahead of Chelsea's match against Burnley on Saturday.
"There's a late change to our starting team. Timo Werner replaces Christian Pulisic and young goalkeeper Karlo Ziger is on the bench," the Blues announced on social media.
No additional details are known about his injury.
Chelsea will certainly miss Pulisic on Saturday after he scored a perfect hat trick in the Blues' 4–2 victory over Burnley last year.
The 22-year-old recently returned from a hamstring injury and didn't start for Chelsea's Champions League match against Krasnodar on Wednesday.