Chelsea French forward Christopher Nkunku will be out for “an extended period” after undergoing surgery on his injured knee.
The 25-year-old suffered the problem during the first half of Chelsea’s pre-season friendly against Borussia Dortmund in Chicago last week.
Chelsea manager Mauricio Pochettino said at the time he hoped the injury would not be a “big issue” for Nkunku.
The Blues, who host Liverpool in their Premier League opener on Sunday, have not specified a length of absence.
However, some reports have suggested the former Paris St-Germain and RB Leipzig forward could be out of action until December.
Nkunku had impressed during Chelsea’s pre-season tour of the United States, scoring three times in five games and displaying a promising link-up with fellow summer signing Nicolas Jackson in attack.
He had scored 58 goals in the past two seasons for Leipzig before finalising a switch to Stamford Bridge in June.
His unavailability is a blow to Pochettino’s new-look Chelsea as they bid to improve on a poor goal record that saw them score just 38 times in the Premier League last season on the way to a 12th-place finish.
