Manchester City manager Pep Guardiola "does not know" if England defender Kyle Walker will be fit for the World Cup as he recovers from injury.
Walker, 32, picked up an abdominal injury in the 6-3 victory over rivals Manchester United on 2 October and was substituted after 41 minutes.
He has 70 caps for England but has just over six weeks to return before the World Cup.
"It's something abdominal and he will be a while out," said Guardiola.
"I don't know [how long]. I cannot say anything else. We have to speak to the doctors. Hopefully he can get back like Kalvin [Phillips].
"I know how important the World Cup is for the players but honestly I don't know right now."
Walker missed City's 5-0 Champions League win over Copenhagen on Wednesday night as they maintained their 100% record in the competition this season.
The defender was named in England manager Gareth Southgate's latest squad in September for the Nations League defeat to Italy and the draw with Germany.
The World Cup starts on 20 November in Qatar with England's first game against Iran the following day.
Southgate will name a 26-player squad for the World Cup.