Chelsea striker Nkunku sidelined after knee surgery

Chelsea's new signing Christopher Nkunku is set to be sidelined for an "extended period" after the French forward underwent surgery for a knee injury, the Premier League club said on Tuesday.

The French forward went down clutching his leg after a challenge in the ninth minute of the 1-1 draw with Borussia Dortmund in a pre-season friendly in Chicago.

Nkunku, who was signed for close to 60 million pounds ($76.32 million), came off midway through the first half in discomfort.

"Nkunku has sustained a knee injury which will rule the forward out for an extended period," the club said in a statement.

"The 25-year-old has undergone an operation and will now begin a rehabilitation programme with the club's medical department."

The injury is a blow to Chelsea's plans of returning to the top four this season under new manager Mauricio Pochettino after the London club finished 12th in the 2022-23 campaign.

Nkunku scored 23 times for RB Leipzig across all competitions last season.

($1 = 0.7862 pounds)