Manchester City boss Pep Guardiola has claimed that Kyle Walker will be out for "a while", with the defender facing a battle to be available for the 2022 World Cup.
The 32-year-old was absent for Wednesday's Champions League clash with Copenhagen due to an abdominal injury that he picked up against Manchester United in the Manchester derby on Sunday.
Guardiola was asked about Walker in the aftermath of the 5-0 victory over Copenhagen, and the head coach could not guarantee that the full-back would be available for selection in Qatar.
"It's something abdominal and he will be a while out," Guardiola told reporters. "I don't know (how long). I cannot say anything else.
"Kyle will be out for a bit. We have to speak to the doctors. Hopefully he can get (back for the World Cup) like Kalvin (Phillips). I know how important the World Cup is for the players but honestly I don't know right now."
He was involved in both UEFA Nations League matches against Italy and Germany last month and has made 70 appearances for his country, helping the team reach the semi-finals of the World Cup in 2018 and final of Euro 2020.
England will not play again until the start of the World Cup, with their tournament beginning against Iran on November 21 before also taking on the United States and Wales in the group stage.
Walker had seemingly been set to operate in a back three for the Three Lions this summer, and his absence would cause Southgate a huge problem heading into the tournament.
Man City were five-goal winners over Copenhagen in the Champions League on Wednesday evening, with Erling Braut Haaland scoring two more goals to continue his remarkable start to the campaign.
"What's important is that Erling Haaland has adapted really well. We have the feeling he is happy here. We will try with him and all of them who want to stay to make them happy," said Guardiola.
"In the future, nobody knows, but he is happy. He has settled perfectly, he is incredibly loved and this is the most important thing."
Haaland was substituted at the interval of the match, denying him the chance to score another hat trick, but Guardiola has said that it was vital for the Norway international to have a rest ahead of a busy run of games.
"He has played a lot of minutes. If the game was tight, Erling will continue to play but after that it is better to rest and think about Southampton, a team we were not able to beat last season," he added.
As well as Walker and Phillips, John Stones is also currently on the sidelines for Man City due to a thigh problem, but the centre-back is expected to be available for selection over the next week or so.