Manchester City defender Kyle Walker has undergone surgery after suffering a groin injury in the derby win against Manchester United.

The 32-year-old was substituted in the first half of City's 6-3 Premier League victory at the Etihad Stadium on Sunday.

Manager Pep Guardiola said after Wednesday's Champions League win against Copenhagen that the right-back would be out for "weeks".

That appeared to put Walker's availability for England's World Cup campaign in doubt, and news of an operation may not soothe national boss Gareth Southgate's concerns.

Guardiola said on Wednesday the problem was "something abdominal", with City clarifying on Thursday it was "a groin injury to his left leg".

"The surgery was successful and a more detailed prognosis will be provided in due course," a City statement read. "Everyone at Manchester City wishes Kyle a speedy recovery."

Walker posted a message on social media from his hospital bed, stating: "As players we have to appreciate injuries are part and parcel of the game we love.

"My operation was a success and now I can concentrate on my rehab and getting back to full fitness. I will be supporting my team-mates every day in any way I can."

Walker's absence is a blow to both club and country, having started seven of City's eight Premier League games this term and four of England's Nations League matches since June.

City have 10 matches in all competitions before the season pauses for the World Cup in Qatar, where England commence their campaign on November 21 against Iran.