Chelsea have confirmed Christopher Nkunku has undergone knee surgery.

The France striker suffered the injury in Chicago last Thursday during their 1-1 preseason draw with Borussia Dortmund.

The Blues released a statement earlier today: "Nkunku has sustained a knee injury which will rule the forward out for an extended period.

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

Several media sources say Nkunku isn't expected to be seen again until 2024.